193 resultados para TRANSFER EFFICIENCIES


Relevância:

20.00% 20.00%

Publicador:

Resumo:

This study reports a hybrid of two metal-organic semiconductors that are based on organic charge transfer complexes of 7,7,8,8-tetracyanoquinodimethane (TCNQ). It is shown that the spontaneous reaction between semiconducting microrods of CuTCNQ with Ag+ ions leads to the formation of a CuTCNQ/AgTCNQ hybrid, both in aqueous solution and acetonitrile, albeit with completely different reaction mechanisms. In an aqueous environment, the reaction proceeds by a complex galvanic replacement (GR) mechanism, wherein in addition to AgTCNQ nanowires, Ag0 nanoparticles and Cu(OH)2 crystals decorate the surface of CuTCNQ microrods. Conversely, in acetonitrile, a GR mechanism is found to be thermodynamically unfavorable and instead a corrosion-recrystallization mechanism leads to the decoration of CuTCNQ microrods with AgTCNQ nanoplates, resulting in a pure CuTCNQ/AgTCNQ hybrid metal-organic charge transfer complex. While hybrids of two different inorganic semiconductors are regularly reported, this report pioneers the formation of a hybrid involving two metal-organic semiconductors that will expand the scope of TCNQ-based charge transfer complexes for improved catalysis, sensing, electronics and biological applications.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

100 year old gasoline engine technology vehicles have now become one of the major contributors of greenhouse gases. Plug-in Electric Vehicles (PEVs) have been proposed to achieve environmental friendly transportation. Even though the PEV usage is currently increasing, a technology breakthrough would be required to overcome battery related drawbacks. Although battery technology is evolving, drawbacks inherited with batteries such as; cost, size, weight, slower charging characteristic and low energy density would still be dominating constrains for development of EVs. Furthermore, PEVs have not been accepted as preferred choice by many consumers due to charging related issues. To address battery related limitations, the concept of dynamic Wireless Power Transfer (WPT) enabled EVs have been proposed in which EV is being charged while it is in motion. WPT enabled infrastructure has to be employed to achieve dynamic EV charging concept. The weight of the battery pack can be reduced as the required energy storage is lower if the vehicle can be powered wirelessly while driving. Stationary WPT charging where EV is charged wirelessly when it is stopped, is simpler than dynamic WPT in terms of design complexity. However, stationary WPT does not increase vehicle range compared to wired-PEVs. State-of-art WPT technology for future transportation is discussed in this chapter. Analysis of the WPT system and its performance indices are introduced. Modelling the WPT system using different methods such as equivalent circuit theory, two port network theory and coupled mode theory is described illustrating their own merits in Sect. 2.3. Both stationary and dynamic WPT for EV applications are illustrated in Sect. 2.4. Design challenges and optimization directions are analysed in Sect. 2.5. Adaptive tuning techniques such as adaptive impedance matching and frequency tuning are also discussed. A case study for optimizing resonator design is presented in Sect. 2.6. Achievements by the research community is introduced highlighting directions for future research.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Unidirectional inductive power transfer (UIPT) systems allow loads to consume power while bidirectional IPT (BIPT) systems are more suitable for loads requiring two way power flow such as vehicle to grid (V2G) applications with electric vehicles (EVs). Many attempts have been made to improve the performance of BIPT systems. In a typical BIPT system, the output power is control using the pickup converter phase shift angle (PSA) while the primary converter regulates the input current. This paper proposes an optimized phase shift modulation strategy to minimize the coil losses of a series – series (SS) compensated BIPT system. In addition, a comprehensive study on the impact of power converters on the overall efficiency of the system is also presented. A closed loop controller is proposed to optimize the overall efficiency of the BIPT system. Theoretical results are presented in comparison to both simulations and measurements of a 0.5 kW prototype to show the benefits of the proposed concept. Results convincingly demonstrate the applicability of the proposed system offering high efficiency over a wide range of output power.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Numerical study has been performed in this study to investigate the turbulent convection heat transfer on a rectangular plate mounted over a flat surface. Thermal and fluid dynamic performances of extended surfaces having various types of lateral perforations with square, circular, triangular and hexagonal cross sections are investigated. RANS (Reynolds averaged Navier–Stokes) based modified k–ω turbulence model is used to calculate the fluid flow and heat transfer parameters. Numerical results are compared with the results of previously published experimental data and obtained results are in reasonable agreement. Flow and heat transfer parameters are presented for Reynolds numbers from 2000 to 5000 based on the fin thickness.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The 19 kDa carboxyl-terminal fragment of merozoite surface protein 1 (MSP119) is a major component of the invasion-inhibitory response in individual immunity to malaria. A novel ultrasonic atomization approach for the formulation of biodegradable poly(lactic-co-glycolic acid) (PLGA) microparticles of malaria DNA vaccines encoding MSP119 is presented here. After condensing the plasmid DNA (pDNA) molecules with a cationic polymer polyethylenimine (PEI), a 40 kHz ultrasonic atomization frequency was used to formulate PLGA microparticles at a flow rate of 18 mL h1. High levels of gene expression and moderate cytotoxicity in COS-7 cells were achieved with the condensed pDNA at a nitrogen to phosphate (N/P) ratio of 20, thus demonstrating enhanced cellular uptake and expression of the transgene. The ability of the microparticles to convey pDNA was examined by characterizing the formulated microparticles. The microparticles displayed Z-average hydrodynamic diameters of 1.50-2.10 lm and zeta potentials of 17.8-23.2 mV. The encapsulation efficiencies were between 78 and 83%, and 76 and 85% of the embedded malaria pDNA molecules were released under physiological conditions in vitro. These results indicate that PLGA-mediated microparticles can be employed as potential gene delivery systems to antigen-presenting cells in the prevention of malaria.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Background A novel ultrasonic atomization approach for the formulation of biodegradable poly(lactic-co-glycolic acid) (PLGA) microparticles of a malaria DNA vaccine is presented. A 40 kHz ultrasonic atomization device was used to create the microparticles from a feedstock containing 5 volumes of 0.5% w/v PLGA in acetone and 1 volume of condensed DNA which was fed at a flow rate of 18ml h-1. The plasmid DNA vectors encoding a malaria protein were condensed with a cationic polymer before atomization. Results High levels of gene expression in vitro were observed in COS-7 cells transfected with condensed DNA at a nitrogen to phosphate (N/P) ratio of 10. At this N/P ratio, the condensed DNA exhibited a monodispersed nanoparticle size (Z-average diameter of 60.8 nm) and a highly positive zeta potential of 38.8mV. The microparticle formulations of malaria DNA vaccine were quality assessed and it was shown that themicroparticles displayed high encapsulation efficiencies between 82-96% and a narrow size distribution in the range of 0.8-1.9 μm. In vitro release profile revealed that approximately 82% of the DNA was released within 30 days via a predominantly diffusion controlledmass transfer system. Conclusions This ultrasonic atomization technique showed excellent particle size reproducibility and displayed potential as an industrially viable approach for the formulation of controlled release particles.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Flexor digitorum longus transfer and medial displacement alcaneal osteotomy is a wellrecognised form of treatment or stage II posterior tibial tendon dysfunction. Although excellent short- and medium-term results have been reported, the long-term outcome is unknown. We reviewed the clinical outcome of 31 patients with a symptomatic flexible flatfoot deformity who underwent this procedure between 1994 and 1996. There were 21 women and ten men with a mean age of 54.3 years (42 to 70). The mean follow-up was 15.2 years (11.4 to 16.5). All scores improved significantly (p < 0.001). The mean American Orthopedic Foot and Ankle Society (AOFAS) score improved from 48.4 pre-operatively to 90.3 (54 to 100) at the final follow-up. The mean pain component improved from 12.3 to 35.2 (20 to 40). The mean function score improved from 35.2 to 45.6 (30 to 50). The mean visual analogue score for pain improved from 7.3 to 1.3 (0 to 6). The mean Short Form-36 physical component score was 40.6 (SD 8.9), and this showed a significant correlation with the mean AOFAS score (r = 0.68, p = 0.005). A total of 27 patients (87%) were pain free and functioning well at the final follow-up. We believe that flexor digitorum longus transfer and calcaneal osteotomy provides long-term pain relief and satisfactory function in the treatment of stage II posterior tibial tendon dysfunction.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Achieving high efficiency with improved power transfer range and misalignment tolerance is the major design challenge in realizing Wireless Power Transfer (WPT) systems for industrial applications. Resonant coils must be carefully designed to achieve highest possible system performance by fully utilizing the available space. High quality factor and enhanced electromagnetic coupling are key indices which determine the system performance. In this paper, design parameter extraction and quality factor optimization of multi layered helical coils are presented using finite element analysis (FEA) simulations. In addition, a novel Toroidal Shaped Spiral (TSS) coil is proposed to increase power transfer range and misalignment tolerance. The proposed shapes and recommendations can be used to design high efficiency WPT resonator in a limited space.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The structures of the 1:1 anhydrous salts of nicotine (NIC) with 3,5-dinitrosalicylic acid (DNSA) and 5-sulfosalicylic acid (5-SSA), namely (1R,2S)-1-methyl-2-(3-pyridyl)-1H-pyrrolidin-1-ium 2-carboxy-4,6-dinitrophenolate, C10H15N2+ C7H3N2O7-, (I) and (1R,2S)-1-methyl-2-(3-pyridyl)-1H-pyrrolidin-1-ium 3-carboxy-4-hydroxybenzenesulfonate, C10H15N2+ C7H5O6S-, (II) are reported. The asymmetric units of both (I) and (II) comprise two independent nicotinium cations (C and D) and either two DNSA or two 5-SSA anions (A and B), respectively. One of the DNSA anions shows a 25% rotational disorder in the benzene ring system. In the crystal of (I), inter-unit pyrrolidinium N-H...N(pyridine) hydrogen bonds generate zigzag NIC cation chains which extend along a while the DNSA anions are not involved in any formal inter-species hydrogen bonding but instead form pi--pi associated stacks which parallel the NIC chains along a [ring centroid separation, 3.857(2)A]. Weak C-H...O interactions between chain substructures give an overall three-dimensional structure. With (II), A and B anions form independent zigzag chains with C and D cations, respectively, through carboxylic acid O-H...N(pyridine) hydrogen bonds. These chains, which extend along b are pseudo-centrosymmetrically related and give pi--pi interactions between the benzene rings of anions A and B and the pyridine rings of the NIC cations C and D, respectively [ring centroid separations, 3.6422(19) and 3.7117(19)A]. Present also are weak intermolecular C-H...O hydrogen-bonding interactions between the chains, giving an overall three-dimensional structure.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Over the past decades, universities have increasingly become ambidextrous organizations reconciling scientific and commercial missions. In order to manage this ambidexterity, technology transfer offices (TTOs) were established in most universities. This paper studies a specific, often implemented, but rather understudied type of TTO, namely a hybrid TTO model uniting centralized and decentralized levels. Employing a qualitative research design, we examine how and why the two TTO levels engage in diverse boundary spanning activities to help nascent spin-off companies move through the pre-spin-off process. Our research identifies differences in the types of boundary spanning activities that centralized and decentralized TTOs perform and in the parties they engage with. We find geographical, technological and organizational proximity to be important antecedents of the TTOs’ engagement in external and internal boundary spanning activities. These results have important implications for both academics and practitioners interested in university technology transfer through spin-off creation.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The Commission has been asked to identify appropriate options for reducing entry and exit barriers including advice on the potential impacts of the personal/corporate insolvency regimes on business exits...

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The Commission has released a Draft Report on Business Set-Up, Transfer and Closure for public consultation and input. It is pleasing to note that three chapters of the Draft Report address aspects of personal and corporate insolvency. Nevertheless, we continue to make the submission to national policy inquiries and discussions that a comprehensive review should be undertaken of the regulation of insolvency and restructuring in Australia. The last comprehensive review of the insolvency system was by the Australian Law Reform Commission (the Harmer Report) and was handed down in 1988. Whilst there have been aspects of our insolvency laws that have been reviewed since that time, none has been able to provide the clear and comprehensive analysis that is able to come from a more considered review. Such a review ought to be conducted by the Australian Law Reform Commission or similar independent panel set up for the task. We also suggest that there is a lack of data available to assist with addressing questions raised by the Draft Report. There is a need to invest in finding out, in a rigorous and informed way, how the current law operates. Until there is a willingness to make a public investment in such research with less reliance upon the anecdotal (often from well-meaning but ultimately inadequately informed participants and others) the government cannot be sure that the insolvency regime we have provides the most effective regime to underpin Australia’s commercial and financial dealings, nor that any change is justified. We also make the submission that there are benefits in a serious investigation into a merged regulatory architecture of personal and corporate insolvency and a combined personal and corporate insolvency regulator.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In public transport, seamless coordinated transfer strengthens the quality of service and attracts ridership. The problem of transfer coordination is sophisticated due to (1) the stochasticity of travel time variability, (2) unavailability of passenger transfer plan. However, the proliferation of Big Data technologies provides a tremendous opportunity to solve these problems. This dissertation enhances passenger transfer quality by offline and online transfer coordination. While offline transfer coordination exploits the knowledge of travel time variability to coordinate transfers, online transfer coordination provides simultaneous vehicle arrivals at stops to facilitate transfers by employing the knowledge of passenger behaviours.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

As transnational programs are often advocated as a knowledge transfer opportunity between the partner universities, this case study investigated the knowledge transfer (KT) processes between Indonesian and Australian universities through an undergraduate transnational program partnership (TPP). An inter-organisational KT theoretical framework from the business sector was adapted and used to guide the study. The data were generated through semi-structured interviews with key university officers and document analysis from two partner universities. Based on the thematic analysis of the data, the findings demonstrated that the curriculum mapping process facilitated KT. However, different intentions of the partner universities in establishing the program led to declining interest to conduct more KT when expectations were not met. The Indonesian university’s existing knowledge, acquired from other sources through processes that were serendipitous and based on individual lecturers’ personal experience, meant that KT opportunities through the TPP were not always pursued despite written agreement to exchange knowledge with the Australian partner. While KT most evidently resulted in institutional capacity development for the Indonesian university’s school that managed the TPP, dissemination of knowledge to other units within the university was more challenging due to communication problems between the units. Hence, other universities seeking to conduct KT through TPPs need to understand each partner university's intention in establishing the partnerships, identify the institutions' needs before seeking knowledge input from the partner university and improve the communication between and within the universities for sustainable benefits.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The transition from a steady to an unsteady flow induced by an adiabatic fin on the sidewall of a differentially heated air-filled cavity is numerically investigated. Numerical simulations have been performed over the range of Rayleigh numbers from Ra = 105–109. The temporal development and spatial structures of natural convection flows in the cavity with a fin are described. It has been demonstrated that the fin may induce the transition to an unsteady flow and the critical Rayleigh number for the occurrence of the transition is between 3.72 × 106 and 3.73 × 106. Furthermore, the peak frequencies of the oscillations triggered by different mechanisms are obtained through spectral analysis. It has been found that the flow rate through the cavity with a fin is larger than that without a fin under the unsteady flow, indicating that the fin may improve the unsteady flow in the cavity.