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Performance Enhancement (performance + enhancement)
Selected AbstractsMolecular Motion and Performance Enhancement of BORAZAN Fluorescent DyesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2009Tyler J. Morin Abstract The preparation of three 2,6-dipyrazolyl-4-X-anilines, H(pz2AnX) (X = p -CF3, Cl, tBu) using CuI-catalyzed amination is described. Subsequent reactions of H(pz2AnX) with triphenylboron proceeds with benzene elimination to give the corresponding Ph2B(pz2AnX) compounds in high yields. The Ph2B(pz2AnX) are more highly emissive in the solid state than the previously reported BORAZAN fluorophores, Ph2B(pzAnX), their monopyrazolyl counterparts. As with the Ph2B(pzAnX), the color of emission in Ph2B(pz2AnX) can be tuned simply by varying the para -aniline substituent where the emission of Ph2B(pz2AnX) is red-shifted relative to the corresponding Ph2B(pzAnX) derivatives. The electronic properties were studied by cyclic voltammetry and electronic absorption/emission spectroscopy as well as by density functional calculations (B3LYP/6-31G*). The di-pyrazolyl derivatives exhibit greater stability toward solvolysis and higher photoluminescent quantum yields (despite the red-shift in emission) compared to their monopyrazolyl counterparts presumably due to kinetic stabilization of the chromophore imparted by the second pyrazolyl ligand. For Ph2B(pz2AnX), evidence for intramolecular motion of the diphenylboryl moiety traversing both pyrazolyl groups was detected by variable temperature 1H NMR spectroscopy. The rate increases with increasing electron-donor abilities of the para -aniline substituent.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Performance enhancement of gas turbines by inlet air-cooling in hot and humid climatesINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 10 2006Majed M. Alhazmy Abstract In this paper, a model to study the effect of inlet air-cooling on gas turbines power and efficiency is developed for two different cooling techniques, direct mechanical refrigeration and an evaporative water spray cooler. Energy analysis is used to present the performance improvement in terms of power gain ratio and thermal efficiency change factors. Relationships are derived for an open gas turbine cycle with irreversible compression and expansion processes coupled to air-cooling systems. The obtained results show that the power and efficiency improvements are functions of the ambient conditions and the gas turbine pressure ratio. The performance improvement is calculated for, ambient temperatures from 30 to 50°C, the whole range of humidity ratio (10,100%) and pressure ratio from 8 to 12. For direct mechanical refrigeration air-cooling, the power improvement is associated with appreciable drop in the thermal efficiency. The maximum power gain can be obtained if the air temperature is reduced to its lowest limit that is the refrigerant evaporation temperature plus the evaporator design temperature difference. Water spray cooling process is sensitive to the ambient relative humidity and is suitable for dry air conditions. The power gain and efficiency enhancement are limited by the wet bulb temperature. The performance of spray evaporative cooler is presented in a dimensionless working graph. The daily performance of the cooling methods is examined for an ABB-11D5 gas turbine operating under the hot humid conditions of Jeddah, Saudi Arabia. The results indicate that the direct mechanical refrigeration increased the daily power output by 6.77% versus 2.57% for the spray air-cooling. Copyright © 2005 John Wiley & Sons, Ltd. [source] Performance enhancement of a chemical reactor utilizing flow instability,JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2-3 2003Mohammad F Kabir Abstract A detailed analysis has been performed for a heterogeneous photocatalytic Taylor vortex reactor that uses flow instability to recirculate fluid continually from the vicinity of the rotating inner cylindrical surface to the stationary outer cylindrical surface of an annulus. A comprehensive time accurate computation shows the different stages of flow evolution and the effects of finite length of the reactor in creating eddies, the overall effects of which shows very high efficiency of photocatalytic conversion. The physical arrangement considered is such that pollutant degradation is maximized by a combination of the Controlled Periodic Illumination (CPI) effect and the motion of fluid particles in a specific regime of centrifugal instability. © 2003 Society of Chemical Industry [source] Supporting Bulk Synchronous Parallelism with a high-bandwidth optical interconnectCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 13 2004I. Gourlay Abstract The list of applications requiring high-performance computing resources is constantly growing. The cost of inter-processor communication is critical in determining the performance of massively parallel computing systems for many of these applications. This paper considers the feasibility of a commodity processor-based system which uses a free-space optical interconnect. A novel architecture, based on this technology, is presented. Analytical and simulation results based on an implementation of BSP (Bulk Synchronous Parallelism) are presented, indicating that a significant performance enhancement, over architectures using conventional interconnect technology, is possible. Copyright © 2004 John Wiley & Sons, Ltd. [source] One size does not fit all: how the tobacco industry has altered cigarette design to target consumer groups with specific psychological and psychosocial needsADDICTION, Issue 11 2003Benjamin Lê Cook ABSTRACT Aims To identify whether the tobacco industry has targeted cigarette product design towards individuals with varying psychological/psychosocial needs. Design Internal industry documents were identified through searches of an online archival document research tool database using relevancy criteria of consumer segmentation and needs assessment. Findings The industry segmented consumer markets based on psychological needs (stress relief, behavioral arousal, performance enhancement, obesity reduction) and psychosocial needs (social acceptance, personal image). Associations between these segments and smoking behaviors, brand and design preferences were used to create cigarette brands targeting individuals with these needs. Conclusions Cigarette brands created to address the psychological/psychosocial needs of smokers may increase the likelihood of smoking initiation and addiction. Awareness of targeted product development will improve smoking cessation and prevention efforts. [source] Development of an Intelligent Data-Mining System for a Dispersed Manufacturing NetworkEXPERT SYSTEMS, Issue 4 2001H.C.W. Lau Recent advances related to on-line analytical processing (OLAP) have resulted in a significant improvement in data analysis efficiency by virtue of its multidimensional database structure and pre-computing operations of measuring data. However, the research related to the design and implementation of OLAP, particularly in the support of dispersed manufacturing networks in terms of ,intelligent decision making', has yet to be considered as remarkable. Research studies indicate that the level of intelligence of decision support systems can be enhanced with the incorporation of computational intelligence techniques such as case-based reasoning or rule-based reasoning. This paper describes the development of an intelligent data-mining system using a rule-based OLAP approach which can be adopted to support dispersed manufacturing networks in terms of performance enhancement. In this paper, the techniques, methods and infrastructure for the development of such a data-mining system, which possesses certain intelligent features, are presented. To validate the feasibility of this approach, a case example related to the testing of the approach in an emulated industrial environment is covered. [source] Achieving performance enhancement in IEEE 802.11 WLANs by using the DIDD backoff mechanismINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 1 2007P. Chatzimisios Abstract Wireless local area networks (WLANs) based on the IEEE 802.11 standards have been widely implemented mainly because of their easy deployment and low cost. The IEEE 802.11 collision avoidance procedures utilize the binary exponential backoff (BEB) scheme that reduces the collision probability by doubling the contention window after a packet collision. In this paper, we propose an easy-to-implement and effective contention window-resetting scheme, called double increment double decrement (DIDD), in order to enhance the performance of IEEE 802.11 WLANs. DIDD is simple, fully compatible with IEEE 802.11 and does not require any estimation of the number of contending wireless stations. We develop an alternative mathematical analysis for the proposed DIDD scheme that is based on elementary conditional probability arguments rather than bi-dimensional Markov chains that have been extensively utilized in the literature. We carry out a detailed performance study and we identify the improvement of DIDD comparing to the legacy BEB for both basic access and request-to-send/clear-to-send (RTS/CTS) medium access mechanisms. Copyright © 2006 John Wiley & Sons, Ltd. [source] A low complexity partially adaptive CDMA receiver for downlink mobile satellite communicationsINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 1 2003Gau-Joe Lin Abstract A novel CDMA receiver with enhanced interference suppression is proposed for pilot symbols assisted mobile satellite systems in the presence of frequency offset. The design of the receiver involves the following procedure. First, adaptive correlators are constructed at different fingers, based on the scheme of generalized sidelobe canceller (GSC), to collect the multipath signals and suppress multi-access interference (MAI). In particular, a partially adaptive (PA) realization of the GSC correlators is proposed based on the Krylov subspace technique, leading to an efficient algorithm without the need of complicated matrix computations. Second, pilot symbols assisted frequency offset estimation, channel estimation and RAKE combining give the estimate of signal symbols. Finally, further performance enhancement is achieved by an iterative scheme in which the signal is reconstructed and subtracted from the GSC correlators input, leading to faster convergence of the receiver. The proposed low complexity PA receiver is suitable or the downlink of mobile satellite CDMA systems, and shown to outperform the conventional fully adaptive MMSE receiver by using a small number of pilot symbols. Copyright © 2003 John Wiley & Sons, Ltd. [source] Enhanced performance by inserting ultrathin SiO2 layer in organic light-emitting devicesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2007Lianbin Niu Abstract Improved performance of organic light-emitting devices (OLEDs) has been obtained by insertion of an ultrathin film of silicon oxide (SiO2) at the interface of 8-hydroxyquinoline aluminum (Alq3) and N,N ,-bis(1-naphthyl)- N,N ,-diphenyl-1,1,-biphenyl-4,4,-diamine (NPB) layers. When a 1.0 nm SiO2 film was inserted, for an unoptimized indium,tin oxide (ITO)/NPB/SiO2/Alq3/Al device, the current efficiency was as high as 7.35 cd/A. Compared with conventional devices, a higher efficiency has been achieved. The mechanism of performance enhancement is discussed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Light extraction enhancement of sapphire-free InGaN LEDs using single- and double-side surface roughening techniquesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S2 2009Dong-Sing Wuu Abstract We compare the performance of three types of GaN-based light-emitting diodes (LEDs) epitaxially grown on patterned sapphire substrates (PSSs). For the devices with a single roughened p-GaN surface, the light output power of the original LEDs with the PSS and Ag reflector (Sample A) is lower than that of thin-film LEDs transferred onto Si carriers via glue bonding (Sample B). While the thin GaN LEDs with double-side roughening (both p-GaN and micropillar undoped-GaN surfaces) and glue/Ag omnidirectional reflector (Sample C) shows much higher light output power than that of Sample B. As compared with the Sample A, the Sample C shows a performance enhancement of 50.3% in light output power and 46.3% in power efficiency at 350 mA. These results reflect that the contribution of the micropillar undoped-GaN texturing for the light extraction is dominant. The employment of Si carrier decreases the junction temperature of the Sample C, a 46.6 °C lower than that of the conventional LEDs on PSS. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Developing strategies for detection of gene dopingTHE JOURNAL OF GENE MEDICINE, Issue 1 2008Anna Baoutina Abstract It is feared that the use of gene transfer technology to enhance athletic performance, the practice that has received the term ,gene doping', may soon become a real threat to the world of sport. As recognised by the anti-doping community, gene doping, like doping in any form, undermines principles of fair play in sport and most importantly, involves major health risks to athletes who partake in gene doping. One attraction of gene doping for such athletes and their entourage lies in the apparent difficulty of detecting its use. Since the realisation of the threat of gene doping to sport in 2001, the anti-doping community and scientists from different disciplines concerned with potential misuse of gene therapy technologies for performance enhancement have focused extensive efforts on developing robust methods for gene doping detection which could be used by the World Anti-Doping Agency to monitor athletes and would meet the requirements of a legally defensible test. Here we review the approaches and technologies which are being evaluated for the detection of gene doping, as well as for monitoring the efficacy of legitimate gene therapy, in relation to the detection target, the type of sample required for analysis and detection methods. We examine the accumulated knowledge on responses of the body, at both cellular and systemic levels, to gene transfer and evaluate strategies for gene doping detection based on current knowledge of gene technology, immunology, transcriptomics, proteomics, biochemistry and physiology. Copyright © 2008 John Wiley & Sons, Ltd. [source] Effects of a supervisory intervention on assessment of interobserver agreement by educational service providersBEHAVIORAL INTERVENTIONS, Issue 2 2008Meredith L. Garrity Effective data collection requires routine assessment of interobserver agreement (IOA). This study evaluated a supervisory intervention to increase the frequency of IOA assessments performed by educational staff at a school for children with developmental disabilities. Intervention components included action directives, strategic posting of IOA recording forms, and performance feedback (positive reinforcement and correction). Implemented in a multiple baseline design, intervention increased IOA assessments targeting skill acquisition and behavior support plans. The study illustrates a systems-level approach towards performance enhancement of human services personnel. Copyright © 2008 John Wiley & Sons, Ltd. [source] Layered view of QoS issues in IP-based mobile wireless networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 2 2006Haowei Bai Abstract With the convergence of wireless communication and IP-based networking technologies, future IP-based wireless networks are expected to support real-time multimedia. IP services over wireless networks (e.g. wireless access to Internet) enhance the mobility and flexibility of traditional IP network users. Wireless networks extend the current IP service infrastructure to a mix of transmission media, bandwidth, costs, coverage, and service agreements, requiring enhancements to the IP protocol layers in wireless networks. Furthermore, QoS provisioning is required at various layers of the IP protocol stack to guarantee different types of service requests, giving rise to issues related to cross-layer design methodology. This paper reviews issues and prevailing solutions to performance enhancements and QoS provisioning for IP services over mobile wireless networks from a layered view. Copyright © 2006 John Wiley & Sons, Ltd. [source] Redesigning alkylated diphenylamine antioxidants for modern lubricantsLUBRICATION SCIENCE, Issue 1 2007Vincent J. Gatto This paper describes a new alkylation technology that is very effective at synthesizing structurally different alkylated diphenylamine chemistries relative to those currently available to lubricant formulators. Examples are provided showing how this technology can be used in a practical way to produce a variety of chemically modified nonylated diphenylamine types. One example is also provided illustrating the preparation of a higher molecular weight dodecylated diphenylamine. Engine oil performance data utilizing pressurized differential scanning calorimetry (PDSC), the thermo-oxidation engine oil simulation test, and a bulk oil oxidation test demonstrate that subtle changes in alkylated diphenylamine chemical composition can result in significant oxidation and deposit control performance enhancements or losses. Examples of similar performance responses in industrial oils are demonstrated utilizing PDSC and the rotating pressure vessel oxidation test. These performance changes are directly related to specific structural changes in the modified products. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||||||||