Platinum@Hexaniobate Nanopeapods: Sensitized Composite Architectures for Photocatalytic Hydrogen Evolution Under Visible Light Irradiation

Hydrogen fuel is one of the most important areas of research in the field of renewable energy development and production. Hydrogen gas can be generated by fuel cells, water electrolyzers, and heterogeneous nanoscale catalysts. It can be burned to directly release chemical energy or condensed for storage and transport, providing fuel for combustion devices or storing excess energy generated by renewable sources such as wind turbines and concentrated solar power assemblies. While platinum is the most active catalyst for hydrogen reduction, its high cost significantly deters its utilization in advanced photocatalytic materials. One approach to mitigating this expense is optimizing the morphology and placement of nanostructured platinum catalysts. Highly crystalline, morphologically-controlled platinum nanoparticles (Pt NPs) have been effectively utilized to increase hydrogen generation efficiency in a variety of nanocomposite materials. However, synthesis routes to high-quality Pt NPs can be dangerous and difficult to replicate. Furthermore, utilization of the Pt NPs in nanocomposite materials is hindered by lack of control over catalyst placement. Nanopeapods are versatile nanocomposites that offer a high degree of control over catalyst placement as well as the potential for interesting new properties arising from the interaction between the catalyst and a semiconductor. Platinum@hexaniobate nanopeapods (Pt@HNB NPPs) consist of linear arrays of Pt NPs encapsulated within the scrolled semiconductor hexaniobate. Pt@HNB NPPs offer significant advantages over similar composites by utilizing the isolated reduction environment of the encapsulated Pt NP arrays to decrease kinetic competition and surface crowding. This work describes the design, fabrication, and implementation of the new nanocomposite platinum@hexaniobate nanopeapods for sensitized hydrogen production under visible light irradiation. The following chapters present facile microwave heating syntheses of highly crystalline Pt nanocubes and Pt@HNB NPPs with consistent morphology and high catalyst loading. A detailed study is also presented of the optical properties of the Pt nanocubes, which produced a UV-range absorbance band that indicates the formation of a localized surface plasmon resonance. Most significantly, preliminary results from visible light photolysis indicate that sensitized Pt@HNB NPPs produce hydrogen in quantities comparable to published systems, and that alteration of experimental parameters may result in even greater yields

A score complete without themes: Henry Mancini and the frenzy experience

This dissertation examines the musical features of, and circumstances surrounding, the film score composed in 1971 by Henry Mancini for director Alfred Hitchcock's penultimate work, Frenzy. Mancini's music was rejected by Hitchcock, and replaced with a markedly different work written by British composer Ron Goodwin. A summation of characteristic traits emerging from Mancini's compositional style is herewith considered, as recurring features found in his thematic writing - aspects of melody, harmony, rhythm, timbre, and form - were most apparent to the non-musician film directors who engaged his services. This summation also includes an examination of the composer's dramatic underscore writing; an aspect of film music often overlooked in its minutiae by viewers and filmmakers alike, and, in the case of Mancini's Frenzy music, characteristic of his scores for Laslo Benedek's 1971 production, The Night Visitor, and Terrence Young's Wait Until Dark, from 1967. Mancini's Frenzy cue sheets, holograph, and recording were supplied by the composer's estate, allowing for an analysis which considers cue placement and length, systems of pitch and rhythmic organisation, aspects of arrangement and orchestration, and conducting and recording methods as practised by this composer. A comparison to the Goodwin score, reproduced by way of transcription from the film, is undertaken in order to explore aspects of filmic point-of-view as they play on the composer of its accompanying music, and to attempt a rationalisation of Hitchcock's displeasure with Mancini's music. Socio-cultural considerations pertaining to Mancini, Goodwin, and the three composer's most favoured by the director for his American productions - John Waxman, Dmitri Tiomkin and Bernard Herrmann - are included in a brief biographical study of each man, as are the musicological characteristics found in the work they undertook for Hitchcock; characteristics primarily of melodicism, and the subjection of melody-based thematic material to extensive modification and repetition. This work suggests that Mancini's admitted refusal, both in his 1987 autobiography Did They Mention the Music? and in subsequent interviews, to construct melodic themes as a unifying element within his score, opting instead to craft timbral unifiers through orchestration, was at the heart of his artistic conflict with Hitchcock

Leveraging Cataloging and Collection Development Expertise to Improve OER Discovery

While there is ongoing improvement in some of the larger open educational resources (OER) search engines, librarians sending emails to listservs asking “anyone know of OER on this topic?” and keeping old-fashioned reading lists of valuable OER are common occurrences. Compared to searching for books in a library catalog or scholarly articles in a research database, finding OER wherever they may be is challenging even for librarians, not to mention instructional faculty. The reason is technical: subpar and variable metadata in OER search engines leads to difficulties searching, capturing, and sharing data across repositories. In other words, the current lack of robust, descriptive metadata for OER results in fewer access points. Thus, OER are comparatively hard to find. Bibliographic control for purposes of information storage and retrieval is something librarians are experts in, but we have not shared our methods with the Open Education community yet. So far, the majority of library advocates for OER have been reference and instruction librarians, as well as library directors. This is great, and we need them to continue to champion OER creation and adoption, but the Open Education movement needs technical services librarians to step forward and apply their cataloging and systems administration expertise to streamline access to the sprawling landscape of OER content; our profession would do well to share our collection development expertise as well. To this end, Clare Sobotka, Reference Assistant at Linn-Benton Community College (LBCC), Holly Wheeler, Library Cataloging and Metadata Specialist at Mt. Hood Community College (MHCC), and Heather White, Library Technical Services & OER Coordinator, along with their colleagues, have started to experiment with creating collection development policies and MARC records for OER. Ultimately, they hope for the development of a metadata schema that is shared between the Open Education and library communities and is mapped to MARC and RDA, to improve both catalog records and OER search engines across the web

Power conversion for a novel AC/DC aircraft electrical distribution system

This paper proposes a novel and compact AC/DC electrical distribution system for new generation aircraft. In these new aircraft power systems, all loads are fed by two dc bus systems: at 28V and at +/-270V. The electrical distribution system, whose design and implementation are described in this paper, has only one primary AC source (360-900Hz at 230V) with all the required dc voltage levels being derived from this source. This solution enables elimination of the complex mechanical coupling apparatus currently used, for fixed frequency AC systems, to maintain the generator speed at constant level while the engines operate at variable speed. Under the proposed solution, all conversion stages needed to generate the various output voltage levels are implemented using power converters assembled in one unit. Each converter has a current control loop in order to regulate the output current even during output line short circuits and also to limit the inrush current to the circuit at turn-on. To prove the concept a 5 kW prototype was designed and tested, and demonstrated to meet all the specifications within relevant standards regarding input and output power quality

Self-tuning resonant control of a 7-leg back-to-back converter for interfacing variable speed generators to 4-wire loads

This paper considers the control of a 7-leg back-to-back Voltage Source Inverter (VSI) arrangement feeding a 4-wire load from a 3-phase Permanent Magnet Synchronous Generator (PMSG) operating at variable speed. The PMSG is controlled using a sensorless Model Reference Adaptive System (MRAS) to obtain the rotor position angle. The 7-leg converter is regulated using Resonant Controllers (RCs) at the load side and self-tuning resonant controllers at the generator side. The control system is augmented by a feed-forward compensation algorithm which improves the dynamic performance during transients. Experimental results, obtained from a prototype, are presented and discussed

Robustness analysis and experimental validation of a fault detection and isolation method for the modular multilevel converter

This paper presents a fault detection and isolation (FDI) method for open-circuit faults of power semiconductor devices in a modular multilevel converter (MMC). The proposed FDI method is simple with only one sliding mode observer (SMO) equation and requires no additional transducers. The method is based on an SMO for the circulating current in an MMC. An open-circuit fault of power semiconductor device is detected when the observed circulating current diverges from the measured one. A fault is located by employing an assumption-verification process. To improve the robustness of the proposed FDI method, a new technique based on the observer injection term is introduced to estimate the value of the uncertainties and disturbances, this estimated value can be used to compensate the uncertainties and disturbances. As a result, the proposed FDI scheme can detect and locate an open-circuit fault in a power semiconductor device while ignoring parameter uncertainties, measurement error and other bounded disturbances. The FDI scheme has been implemented in a field programmable gate array (FPGA) using fixed point arithmetic and tested on a single phase MMC prototype. Experimental results under different load conditions show that an open-circuit faulty power semiconductor device in an MMC can be detected and located in less than 50ms

Control of a hybrid modular multilevel converter during grid voltage unbalance

The recently proposed parallel hybrid modular multilevel converter is considered to be a low loss, low component count converter with soft switching capability of the ‘main’ bridge. The converter has similar advantages to other emerging modular multilevel converter circuits being considered for HVDC power transmission. However, during ac network unbalance the individual ‘chain-links’ exchange unequal amounts of power with the grid which requires appropriate remedial action. This paper presents research into the performance of the converter and proposes a suitable control method that enables the converter to operate during grid voltage unbalance. The proposed control concept involves the use of asymmetric third harmonic voltage generation in the ‘chain-links’ of the converter to redistribute the power exchanged between the individual ‘chain-links’ and the grid. Mathematical analysis and simulation modelling with results are presented to support the work described

Fault detection for modular multilevel converters based on sliding mode observer

This letter presents a fault detection method for modular multilevel converters (MMC) which is capable of lo¬cating a faulty semiconductor switching device in the circuit. The proposed fault detection method is based on a sliding mode observer (SMO) and a switching model of a half-bridge, the approach taken is to conjecture the location of fault, modify the SMO accordingly and then compare the observed and measured states to verify, or otherwise, the assumption. This technique requires no additional measurement elements and can easily be implemented in a DSP or micro-controller. The operation and robustness of the fault detection technique are confirmed by simulation results for the fault condition of a semiconductor switching device appearing as an open-circuit