Energy saving optimal design and control of electromagnetic brake on passenger car

In this paper, the optimal design and control method of electromagnetic brake for a typical city driving cycle are studied to improve its energy consumption characteristics. The prediction models of the braking performance and power consumption for electromagnetic brake were established, and their accuracies were verified on the hardware of the loop simulation platform. Moreover, the energy consumption based on the ECE-EUDC driving condition was taken as the objective function, and a mathematical model for the optimal design of the electromagnetic brake was established. Genetic Algorithm was used to seek global optimal solution of these design variables on the premise of the given electrical and space constraints. Finally, the effect of thermodynamic properties of electromagnetic brake on the energy consumption characteristics was analyzed, and the energy saving control method of electromagnetic brake was also proposed. Experimental results show that the energy saving optimal design and control that this paper investigates can significantly improve the energy efficiency of electromagnetic brake.</p

Analysis of far-infrared optical spectra of multiferroics

The optical spectra of multiferroic crystals Dy3Fe5O12, Tb3Fe5O12, and four hexagonal RMnO3 (5D= Er, Tm, Yb, Lu) are studied using intense bright synchrotonic light in the infrared spectral range. In regards to the materials analyzed, two rare earth iron garnets and four rare earth manganites in total are examined. These materials have attracted much attention due to their interesting magnetoelectric properties. They could serve as the basis for the next generation of faster and more energy efficient memory and logic devices. To examine these materials, two optical techniques were utilized: transmission spectroscopy and rotating analyzer ellipsometry. Transmission spectroscopy experiments analyze absorption of light passed through a material. Ellipsometry examines the change of polarization state for a reflected beam of light. Work has been done at the Brookhaven National Laboratory - National Synchrotron Light Source. Requisite for this project is a pair of broadband retarders for far- IR spectral range. Several retarders are devised to accomplish this task. They were designed using computer simulations and calculations before they are fabricated. Work towards the development of these retarders is included in this dissertation. Ferrimagnetic Dy3Fe5O12 single crystals are studied in the spectral range between 12 and 700 cm-1, and in a wide temperature range between 5 K and 300 K using transmission spectroscopy and rotating analyzer ellipsometry (RAE). It is found that in the temperature range below TC=16 K for the magnetic ordering of Dy3+ spins, a number of ligand field (L F) and Kaplan-Kittel (KK) exchange resonance modes emerge. Temperature dependences of their frequencies allowed us to estimate the ratio between the Fe-Dy and Dy-Dy exchange constants. Tb3Fe5O12 single crystals are studied in the range between 15 and 100 cm-1, in magnetic fields up to 10 T, and for temperatures between 5 and 150 K using only transmission spectroscopy. A number of IR active excitations are attributed to electric- dipole transitions between ligand-field splitting of Tb3+. Anticrossing between the magnetic exchange excitation and the ligand-field transition occurs at the temperature between 60 and 80 K. The corresponding coupling energy for this interaction is 6 cm-1. Temperature-induced softening of the hybrid IR excitation correlates with the increase of the static dielectric constant in Tb3Fe5O12. The hexagonal RMnO3 (5 = Er, Tm, Yb, Lu) single crystals are studied between 8 and 125 cm-1, in fields up to 9T and for temperatures from 1.5 to 100 K. It is observed that the magnon frequency increases systematically with a decrease of the rare earth ion radius. The magnetic ordering of R ions (R=Er, Tm, Yb) is seen at low temperatures T\u3c3.5 K and in strong external magnetic fields. The observed effects are analyzed taking into account main magnetic interactions in the system including exchange of the Mn3+ spins with R3+ paramagnetic moments

Development of high temperature containerless processing equipment and the design and evaluation of associated systems required for microgravity materials processing and property measurements

The development of high temperature containerless processing equipment and the design and evaluation of associated systems required for microgravity materials processing and property measurements are discussed. Efforts were directed towards the following task areas: design and development of a High Temperature Acoustic Levitator (HAL) for containerless processing and property measurements at high temperatures; testing of the HAL module to establish this technology for use as a positioning device for microgravity uses; construction and evaluation of a brassboard hot wall Acoustic Levitation Furnace; construction and evaluation of a noncontact temperature measurement (NCTM) system based on AGEMA thermal imaging camera; construction of a prototype Division of Amplitude Polarimetric Pyrometer for NCTM of levitated specimens; evaluation of and recommendations for techniques to control contamination in containerless materials processing chambers; and evaluation of techniques for heating specimens to high temperatures for containerless materials experimentation

Multilayered Planar Periodic Subwavelength Microstructures For Generating And Detecting Circularly Polarized Thermal Infrared Radiation

Generation and detection of circularly-polarized (CP) radiation in the 8- to 12-μm band of the infrared (IR) spectrum is crucial for polarization sensing and imaging scenarios. There is very little naturally occurring CP radiation in the long-wave IR band, so that useful functionalities may be obtained by exploiting preferential radiation and transmission characteristics of engineered metamaterials. Conventional CP devices in the IR utilize birefringent crystals, which are typically bulky and expensive to manufacture. The operation of these devices is generally optimized at a single wavelength. Imaging in the long-wave IR is most often broadband, so that achromatic CP-device behavior is highly desirable from a fluxtransfer viewpoint. Also, size, weight and cost are significant drivers in the design of practical IR systems. Thus a solution is sought with a convenient thin planar form factor. This dissertation will demonstrate a novel planar periodic subwavelength-microstructured approach derived from classical radiofrequency meanderline designs that are able to generate CP radiation over a broad IR band while maintaining a low fabrication profile. We investigate issues regarding efficiency as a function of the number of layers in the device structure; reflective, transmissive, and emissive behavior; strategies for broadband achromatization; and thermal-isolation requirements between the active blackbody reservoir and the top of the planar device, to achieve a given degree of polarization. Theoretical, numerical, and experimental findings are presented that confirm the feasibility of this class of devices for use in a wide variety of situations, from polarization imaging and spectroscopy to industrial laser processing and machining

Resonance fluorescence of novel quantum emitters

Quantum dots (QD) emitting near the telecommunication O-band and excitons believed to be localized on defects in WSe2 monolayers are investigated using optical spectroscopy and resonance fluorescence (RF). The development of light sources emitting around 1300 nm is motivated primarily by the possibility of their use in information communication applications. The results presented in this thesis pave the way towards coherently generated indistinguishable single photons and entangled photon pairs at telecom wavelengths. WSe2 monolayers are highly stable and are characterized by a higher extraction efficiency of photons compared to photon sources embedded in bulk materials. The experiments on confined excitons described here set the stage for the characterization of the effect of valley pseudospin on localized exciton emission properties. A perturbative Coulomb blockade model is applied to telecom wavelength QDs to extract confinement and interaction energies, demonstrating that carriers are in the strong confinement regime. To examine the effect of strong confinement on carrier properties, photoluminescence (PL) spectroscopy of single QDs in the pres- ence of external electric and magnetic fields is performed, and the permanent dipole moment, polarizability, diamagnetic coefficient, and g-factor of excitons localized within them are measured. Temporal measurements on neutral and charged exci- tons are performed, and a bi-exponential decay is observed in the former case, which necessitates a spin-flip interaction with the Fermi sea. RF of telecom wavelength QDs is demonstrated, and numerical simulations are used to characterize the effect of spectral fluctuations resultant from charge noise on RF linewidth. Performing high-resolution spectroscopy, the Mollow triplet is observed and dephasing in the system is shown to be negligible. Second-order correlation function measurements of emission from a localized ex- citon in a WSe2 monolayer cooled to 4 K under non-resonant and resonant excitation demonstrate its single photon nature. High-resolution PL excitation spectroscopy is used to identify a weakly-fluorescent exciton state blue-shifted from the ground- state exciton. Resonance excitation of the blue-shifted exciton is shown to produce single photons of high purity from the lowest energy exciton state

Characterization of laser-produced plasmas as light sources for extreme ultraviolet lithography and beyond

2019 Fall.Includes bibliographical references.Lithography is a critical process in the fabrication of integrated circuits. The continuous increase in computing power for more than half a century has depended in the ability to print smaller and smaller features, which has required the use of light sources operating at increasingly shorter wavelengths. There is keen interest in the development of high-power light sources for extreme ultraviolet (EUV) lithography at λ=13.5 nm and future beyond extreme ultraviolet (BEUV) lithography near λ=6.7 nm. The work conducted in this dissertation has characterized aspects of laser-produced plasmas (LPPs) that serve as light sources for EUV / BEUV lithography. The laser pulse shape dependence of the conversion efficiency of λ=1.03 μm laser into in-band 13.5 nm EUV emission in a Sn LPP was studied as a function of laser pulse shape and durations. Laser pulses of arbitrary temporal shape with variable energy and pulse widths were generated using a programmable pulse synthesizer based on a diode-pumped chirped pulse amplification Yb: YAG laser. The pulse synthesizer is based on wave front splitting and pulse stacking for the generation of arbitrary shape laser pulses of Joule-level energy. Pulses ranging from hundreds of ps to several ns were generated with a single laser. The measurements showed the CE favors the use of nearly square pulses of duration longer than 2 ns, in agreement with hydrodynamic/atomic physics simulations. A significant increase in CE was observed when Q-switched pulses were substituted by square pulses of similar duration. Conditions were observed at which the EUV pulse duration significantly outlasts the laser pulse in the direction normal to the target surface, in contrast at grazing angles the measured EUV pulse duration is shorter and similar to the laser pulse duration. The physics leading to this angular anisotropy is discussed, along with the spectroscopic characterization of EUV emission and at-wavelength images that characterize the source size. Another aspect of this dissertation includes a comprehensive study of the emission from Gd and Tb LPPs in the λ=6.5 - 6.7 nm region. BEUV emission spectra were measured as a function of laser pulse duration (120 ps - 4 ns), emission angle, and spatial location within the plasma. At-wavelength images of the BEUV emitting plasma region were obtained as a function of irradiation parameters. The peak of the emission spectrum was observed to broaden and to shift to longer wavelengths as the laser pulses are shortened from ns to hundreds of ps. Transient self-consistent hydrodynamic/atomic physics simulations show that the picosecond irradiation creates significantly hotter plasmas in which the dominant emission originates from more highly ionized species. Gd LPP emission driven by nanosecond laser pulses best matched the reflectivity band of our La/B4C mirrors. Spatially resolved spectra of the Gd LPP were acquired for different laser parameters and were compared to simulations. The CE into in-band BEUV emission was determined by integrating angularly resolved measurements obtained using an array of calibrated energy monitors. A maximum CE of 0.47% / 0.45% for the Gd / Tb LPPs was obtained within a 0.6% bandwidth. The results are of potential interest BEUV lithography

A Broadly Tunable Surface Plasmon-Coupled Wavelength Filter for Visible and Near Infrared Hyperspectral Imaging

Hyperspectral imaging is a set of techniques that has contributed to the study of advanced materials, pharmaceuticals, semiconductors, ceramics, polymers, biological specimens, and geological samples. Its use for remote sensing has advanced our understanding of agriculture, forestry, the Earth, environmental science, and the universe. The development of ultra-compact handheld hyperspectral imagers has been impeded by the scarcity of small widefield tunable wavelength filters. The widefield modality is preferred for handheld imaging applications in which image registration can be performed to counter scene shift caused by irregular user motions that would thwart scanning approaches. In the work presented here an electronically tunable widefield wavelength filter has been developed for hyperspectral imaging applications in the visible and near-infrared region. Conventional electronically tunable widefield imaging filter technologies include liquid crystal-based filters, acousto-optic tunable filters, and electronically tuned etalons; each having its own set of advantages and disadvantages. The construction of tunable filters is often complex and requires elaborate optical assemblies and electronic control circuits. I introduce in the work presented here is a novel widefield tunable filter, the surface plasmon coupled tunable filter (SPCTF), for visible and near infrared imaging. The SPCTF is based on surface plasmon coupling and has simple optical design that can be miniaturized without sacrificing performance. The SPCTF provides diffraction limited spatial resolution with a moderately narrow nominal passband (\u3c10 \u3enm) and a large spurious free spectral range (450 nm-1000 nm). The SPCTF employs surface plasmon coupling of the π-polarized component of incident light in metal films separated by a tunable dielectric layer. Acting on the π-polarized component, the device is limited to transmitting 50 percent of unpolarized incident light. This is higher than the throughput of comparable Lyot-based liquid crystal tunable filters that employ a series of linear polarizers. In addition, the SPCTF is not susceptible to the unwanted harmonic bands that lead to spurious diffraction in Bragg-based devices. Hence its spurious free spectral range covers a broad region from the blue through near infrared wavelengths. The compact design and rugged optical assembly make it suitable for hand-held hyperspectral imagers. The underlying theory and SPCTF design are presented along with a comparison of its performance to calculated estimates of transmittance, spectral resolution, and spectral range. In addition, widefield hyperspectral imaging using the SPCTF is demonstrated on model sample

Latent structured thermally developed reliefs : principles and applications of photoembossing

In verschillende technologieën worden micro-oppervlaktestructuren in polymeren gebruikt. Voorbeelden hiervan zijn te vinden in optische dataopslag, beeldschermen, microfluidics en coatings. Met het doorzetten van de huidige trend om alles te minutiarizeren is het voor de handliggend dat micro-oppervlaktestructuren een steeds belangrijkere rol zullen gaan vervullen. Hiervoor zullen technieken ontwikkeld moeten worden om nieuwe structuren in massaproductie te kunnen maken. Vanwege de eenvoud van het proces heeft photoembossing de potentie om een dergelijke techniek te zijn. Het basismateriaal bij photoembossing is een dunne film welke bestaat uit een mengsel van een polymeer, een monomeer en een fotoinitiator. Dit mengsel wordt ook wel het fotopolymeer genoemd. Een latent beeld van het gewenste oppervlaktereliëf wordt in het fotopolymeer aangebracht door het lokaal met ultraviolet (UV) licht te belichten. Daardoor wordt de fotoninitiator geactiveerd en ontstaan er radicalen in de belichte gebieden. Het oppervlaktereliëf ontstaat door het fotopolymeer te verwarmen tot boven de glastransitietemperatuur van het mengsel. Hierdoor verhoogt de mobiliteit van het systeem en wordt de radical geïnitieerde polymerisatie doorgezet. Door het lokale verschil in compositie ontstaat diffusie van het monomeer naar de belichte gebieden. De diffusie zorgt voor de groei van oppervlaktestructuren in de belichte gebieden. De maximale aspect ratio (hoogte van de structuur gedeeld door de breedte) die momenteel met deze techniek gehaald kan worden is echter laag. Dit beperkt het aantal applicaties waar de techniek potentieel gebruikt zou kunnen worden. In dit proefschrift worden verschillende methodes gepresenteerd om de aspect ratio van de oppervlaktestructuren te verbeteren. Tevens worden nieuwe applicaties voor deze unieke techniek gedemonstreerd. Allereerst, is het ontstaan van de oppervlaktestructuren onderzocht door middel van een numeriek model. Dit model omschrijft de diffusie van het monomeer als gevolg van een lokale verandering in het chemisch potentiaal, wat ontstaat door de polymerisatiereactie in de belichte gebieden. Het effect van componenten die interfereren met de polymerisatiereactie (zoals bv. zuurstof) is meegenomen in het model. Het model laat zien dat terminatie van de radicalen, met name door trapping, een belangrijke factor is in het ontwikkelingsproces van het reliëf. Moleculen die de terminatie van radicalen bevorderen (zoals bv. zuurstof) hebben dan ook een negatief effect op de hoogte van het reliëf. Moleculen die de polymerisatiereactie herinitiëren na reactie met de radicalen (zoals bv. chain transfer agents) hebben een positief effect op de structuurgroei. De transfer/reinitiatie reactie zorgt voor ophoping van gestabiliseerde radicalen. Deze radicalen dienen als "latente initiatoren" die tijdens de verwarmingstap de polymerisatiereactie kunnen voortzetten. Door aan het fotopolymeer moleculen toe te voegen die de terminatie van radical bevorderen (inhibitors/retarders) en die de polymerisatiereactie reinitiëren (chain transfer) zijn de modelresultaten experimenteel onderzocht. Aangetoond is dat een inhibitiereactie een negatief effect heeft op de structuurgroei. Retardatie daar en tegen zorgt voor verbetering van de aspect ratio tot een factor 7. Onderzoek naar het type radicaal, de stabiliteit van de radicalen en het kinetisch effect op de reactie toont aan dat deze verbetering toegeschreven kan worden aan chain transfer reacties. Het effect van de chain transfer reactie is nader onderzocht door het toevoegen van reversibele addition-fragmentation (RAFT) agents. Ook deze moleculen verbeterden de structuurhoogte van het reliëf tot een factor 7. De RAFT agents hebben het voordeel dat ze ongevoelig zijn voor de aanwezigheid van zuurstof in de omgeving, wat ideaal is voor industriële applicaties. Helaas, maakt hun intrinsieke kleur ze minder geschikt voor optische toepassingen. Om de structuurhoogte verder te verbeteren zijn er nieuwe fotopolymeren ontwikkeld. Anders dan met de conventionele systemen bevatten deze fotopolymeren geen grote hoeveelheid polymeer. Conventioneel bestaat het fotopolymeer tot wel 50 wt.-% aan polymeer om het materiaal na aanbrengen een vaste toestand te geven. Echter het polymeer kan niet diffunderen en draagt daardoor niet bij aan de uiteindelijke structuurhoogte. De nieuw ontwikkelde systemen bestaan uit mobiele monomeren die bij kamertemperatuur in een vaste staat verkeren door sterische of dipool-dipool interacties. Aangetoond is dat in deze nieuwe fotopolymeren relatief hoge structuren gemaakt kunnen worden. De verbeterde performance en warmte geïnitieerde reliëfontwikkeling maken het mogelijk om photoembossing te gebruiken voor unieke applicaties. Aangetoond wordt dat de techniek gebruikt kan worden om een array van microlenzen met een antireflectie coating te maken. De optische eigenschappen van de lenzen kunnen eenvoudig aangepast worden door de procesparameters te veranderen. Photoembossing kan ook gebruikt worden om in-situ een array van gevulde microbakjes (zoals bv. in een electroforetische display) hermetisch te sluiten. Het concept is ongevoelig voor kleine afwijkingen in de hoogte van de wanden van de bakjes, vlakheid van het dekglas en dunne vloeistoflaagjes die achterblijven tussen het dekglas en wanden van de bakjes. Een andere eigenschap van photoembossing is dat zowel de materiaal- als productiekosten laag zijn. De techniek kan hierdoor gebruikt worden om een reliëf voor het verbeteren van de kijkhoek van displays, wegwerpbare replicatiemallen of stempels te maken. Bij photoembossing wordt een reliëfstructuur gemaakt door diffusie van moleculen naar van te voren bepaalde gebieden. Het omgekeerde, reliëfstructuren die de diffusie van moleculen induceren, is ook mogelijk. Dit effect wordt gebruikt in biosensoren. Deze apparaten detecteren briomoleculaire stoffen, zoals bv DNA/RNA of proteïnen, in vloeistoffen. De huidige systemen hebben ofwel kleine volumes aan monstervloeistof nodig ofwel een hoge gevoeligheid. In dit proefschrift wordt een nieuw type sensor, welke een klein monstervolume combineert met een hoge gevoeligheid, ontworpen, gemaakt en geëvalueerd. Het apparaat is gebaseerd op een microfluidic kanaal waarin een lokaal poreus membraan is aangebracht. De sensor kan in principe hermetisch afgesloten worden door middel van photoembossing. Samengevat is er aangetoond dat het mogelijk is om reliëfstructuren met een hoge aspect ratio te krijgen door middel van photoembossing. De verbeterde performance kan gebruikt worden voor een aantal nieuwe applicaties en opent een scala aan andere mogelijke toepassing

Organic Light Emitting Devices

This book describes the state-of-the-art advancement in the field of organic electroluminescence contributed by many researchers with internationally established expertise in the field. It includes original contributions on the synthesis of suitable organic materials, fabrication of organic light emitting devices (OLEDs) and organic white light emitting devices (WOLEDs), characterization of these devices and some designs for optimal performance. All chapters are self-sufficient in presenting their contents. The cost effective chemical technology offers many exciting possibilities for OLEDs and organic solar cells (OSCs) to be futuristic solutions for lighting and power generation. A common flexible substrate can be used to fabricate OLEDs on one side facing a room and OSCs on the other side facing the sun. The device thus fabricated can generate power in the day time and light a room/house at night. The book covers developments on OLEDs, WOLEDs and briefly on OSCs as well

LASER Tech Briefs, Spring 1994

Topics in this Laser Tech Brief include: Electronic Components and Circuits. Electronic Systems, Physical Sciences, Materials, Mechanics, Fabrication Technology, and books and reports