Maximum Power Level Research Articles

Compow-Based PCM Protocol for Multi-Hop Manet

In this paper, we propose a power saving scheme that integrates power control MAC (PCM) protocol and COMPOW protocol. The goal of the proposed scheme is to save power and maximize throughput in a multi-hop wireless ad hoc networks. This new protocol works in two phases. First, it uses COMPOW protocol to select the minimum common power (Pcommon) that can be suitable for providing a link from the source to the destination. In the second phase, PCM uses this selected common power (Pcommon) in place of maximum power (P max). Reducing the maximum power level of the control packets RTS-CTS to common power (Pcommon) brings down the interference effects of these packets on the DATA-ACK packets. The second benefit of using common power is significant reduction in carrier sensing range compared to the standard schemes. However, this carrier sensing range is sufficient to avoid the interference among various nodes involved in the multi-hop routing. Avoiding collisions, improving spatial reuse and increasing the contentions between the nodes of the multi-hop wireless ad hoc networks save energy and improve the throughput. In this paper, we have evaluated the performance of our proposed scheme and compared with COMPOW and the standard IEEE 802.11b, BASIC, PCM schemes using MINPOW power aware and conventional routing protocols. Our simulation results show that PCM/COMPOW power saving scheme achieves high reduction in energy consumption.

The Influence of Corona Electrodes Thickness on the Efficiency of Plasmachemical Oxidation of Acetone

Current–voltage characteristics (CVC) and acetone vapors oxidation in atmospheric pressure corona discharge (CD) of negative and positive polarity were studied in double wires-to-plate geometry. Negative CD was more stable than positive one towards breakdown and allowed to reach higher current. CVC for negative CD can be well described by model for cylindrical geometry with correction in one coefficient only. The ignition voltage of negative CD obeys Peek’s law. The rate of acetone vapors oxidation increased with the increase of corona wire radius in the range of discharge power 15–60 W. The highest oxidation rate was obtained at power 60 W, negative polarity and wire radius 400 μm but the highest energetic efficiency (g/kWh) was obtained at maximum wire radius (400 μm) and minimum power level (15 W). The oxidation rate was directly proportional to the volume of discharge area which grows together with the increase of wire radius.

A Multimode/Multiband Power Amplifier With a Boosted Supply Modulator

A multimode/multiband power amplifier (PA) with a boosted supply modulator is developed for handset applications. A linear broadband class-F amplifier is designed to have a constant fundamental impedance across 1.7-2 GHz and its second and third harmonic impedances are located at the high-efficiency area. To reduce the circuit size for handset application, the harmonic control circuits are merged into the broadband output matching circuit for the fundamental frequency. An envelope-tracking operation delivers high efficiency for the overall power. The linearity is improved by envelope tracking (ET) through intermodulation-distortion sweet-spot tracking at the maximum output power level. The efficiency and bandwidth (BW) are enhanced by a boosted supply modulator. Multimode operation is achieved by an ET technique with a programmable hysteresis control and automatic switching current adaptation of the hybrid supply modulator. For demonstration purpose, the PA and supply modulator are implemented using an InGaP/GaAs heterojunction bipolar transistor and a 65-nm CMOS process. For a long-term evolution signal, the envelope-tracking (ET) PA delivers a power-added efficiency (PAE) and an error vector magnitude of 33.3%-39% and 2.5%-3.5%, respectively, at an average power of 27.8 dBm across 1.7-2 GHz. For a wideband code-division multiple-access signal across 1.7-2 GHz, the ET PA performs a PAE, an ACLR1, and an ACLR2 of 40%-46.3%, from -39 to -42.5 dBc, and -51 to -58 dBc, respectively, at an average output power of 30.1 dBm. The ET PA with an EDGE signal delivers a PAE, an ACPR1, and an ACPR2 of 37%-42%, from -56.5 to -59.3 dBc, and -63.5 to -69.5 dBc, respectively, at an average power of 28 dBm across the 300-MHz BW. These results show that the proposed design achieves highly efficient and linear power amplification for multimode/multiband wireless communication applications.

Performance characteristics of a continuous-wave compact widely tunable external cavity interband cascade lasers

We present the design and performance of a novel broadly tunable continuous-wave external-cavity interband cascade laser (ECicL). The ICL die growth and fabrication, as well as the external cavity geometry are described. Tuning across the 3.2-3.35 microm wavelength range, limited by the gain width of the ICL active medium, is achieved at a maximum power level of 4 mW.

Effect of cycling rate, particle size and transport properties on lithium-ion cathode performance

Much progress has been made in modeling the lithium-ion battery technology. There exists a critical need to establish a framework to assess the role of various physical, geometrical, and operating parameters and their relative influence on the energy and power capability of batteries. In this study, a surrogate modeling framework has been introduced to map the effect of design-related parameters on the performance of a lithium-ion cell. In particular, the effects of cycling rate, cathode particle size, and diffusion coefficient and electrical conductivity of the solid cathode material, on the specific energy and power have been studied using a cell-level model in conjunction with tools such as kriging, polynomial response, and radial-basis neural networks. Through global sensitivity analysis the relative impact of the various parameters are quantified under different scenarios. Specifically, the design space can be split into distinct regions based on the discharge and diffusion time scales for separate, more refined analysis. It is shown that the cathode performance becomes independent of the diffusion coefficient above a critical value. A Pareto-optimal front was constructed to quantify the tradeoff between maximum achievable energy and power levels. Such an analysis can provide guidelines for the optimization of the positive electrode design.

A Reduced Number of mtSNPs Saturates Mitochondrial DNA Haplotype Diversity of Worldwide Population Groups

BackgroundThe high levels of variation characterising the mitochondrial DNA (mtDNA) molecule are due ultimately to its high average mutation rate; moreover, mtDNA variation is deeply structured in different populations and ethnic groups. There is growing interest in selecting a reduced number of mtDNA single nucleotide polymorphisms (mtSNPs) that account for the maximum level of discrimination power in a given population. Applications of the selected mtSNP panel range from anthropologic and medical studies to forensic genetic casework.Methodology/Principal FindingsThis study proposes a new simulation-based method that explores the ability of different mtSNP panels to yield the maximum levels of discrimination power. The method explores subsets of mtSNPs of different sizes randomly chosen from a preselected panel of mtSNPs based on frequency. More than 2,000 complete genomes representing three main continental human population groups (Africa, Europe, and Asia) and two admixed populations (“African-Americans” and “Hispanics”) were collected from GenBank and the literature, and were used as training sets. Haplotype diversity was measured for each combination of mtSNP and compared with existing mtSNP panels available in the literature. The data indicates that only a reduced number of mtSNPs ranging from six to 22 are needed to account for 95% of the maximum haplotype diversity of a given population sample. However, only a small proportion of the best mtSNPs are shared between populations, indicating that there is not a perfect set of “universal” mtSNPs suitable for all population contexts. The discrimination power provided by these mtSNPs is much higher than the power of the mtSNP panels proposed in the literature to date. Some mtSNP combinations also yield high diversity values in admixed populations.Conclusions/SignificanceThe proposed computational approach for exploring combinations of mtSNPs that optimise the discrimination power of a given set of mtSNPs is more efficient than previous empirical approaches. In contrast to precedent findings, the results seem to indicate that only few mtSNPs are needed to reach high levels of discrimination power in a population, independently of its ancestral background.

Power Efficiency Comparisons of Interchip Optical Interconnect Architectures

High-bandwidth interchip optical interconnect architectures have the potential to address increasing input-output bandwidth demands. This brief compares several optical interconnect architectures on the basis of power efficiency in 90- and 45-nm CMOS technologies. Under consideration are a near-term architecture consisting of discrete vertical-cavity surface-emitting lasers (VCSELs) with p-i-n photodetectors (PDs) and three long-term integrated photonic architectures that use waveguide metal-semiconductor-metal PDs and either electroabsorption modulator (EAM), ring resonator modulator (RRM), or Mach-Zehnder modulator (MZM) sources. An optimal current density methodology with normalized transistor parameters extracted from circuit simulations is applied to jointly optimize driver and receiver circuitry to minimize the total link power dissipation. The analysis results show that the VCSEL-based link is limited by VCSEL bandwidth and maximum power levels, rather than circuit bandwidth, and achieves a maximum of 24 Gb/s in both the 90- and 45-nm nodes. The EAM and the RRM are both attractive integrated photonic technologies capable of scaling data rates past 30 Gb/s at power efficiency levels near 0.5 mW/Gb/s in the 45-nm node and are primarily limited by coupling and device insertion losses. While the MZM offers robust operation due to its wide optical bandwidth, significant improvements in power efficiency must be achieved to become applicable for high-density applications.

Applications of Low-Speed Dynamic-Stall Model to the NREL Airfoils

National Renewable Energy Laboratory, USA (NREL) airfoils have been specially developed for wind turbine applications, and projected to yield more annual energy without increasing the maximum power level. These airfoils are designed to have a limited maximum lift and relatively low sensitivity to leading-edge roughness. As a result, these airfoils have quite different leading-edge profiles from airfoils applied to helicopter blades, and thus, quite different dynamic-stall characteristics. Unfortunately for wind turbine aerodynamics, the dynamic-stall models in use are still those specially developed and refined for helicopter applications. A good example is the Leishman–Beddoes dynamic-stall model, which is one of the most popular models in wind turbine applications. The consequence is that the application of such dynamic-stall model to low-speed cases can be problematic. Recently, some specific dynamic-stall models have been proposed or tuned for the cases of low Mach numbers, but their universality needs further validation. This paper considers the application of the modified dynamic low-speed stall model of Sheng et al. (“A Modified Dynamic Stall Model for Low Mach Numbers,” 2008, ASME J. Sol. Energy Eng., 130(3), pp. 031013) to the NREL airfoils. The predictions are compared with the data of the NREL airfoils tested at the Ohio State University. The current research has two objectives: to justify the suitability of the low-speed dynamic-stall model, and to provide the relevant parameters for the NREL airfoils.

Effect of different handgrip angles on work distribution during hand cycling at submaximal power levels

The effect of different handle angles on work distribution during hand cycling was determined. Able-bodied subjects performed hand cycling at 20% of maximum power level (mean (SD) power level: 90.0 (25.8) W) at a cadence of 70 rpm using handle angles of ±30°, ±15° and 0°. The handle angle had a significant effect on work during the pull down (p < 0.001) and lift up (p = 0.005) sector, whereby the highest work was performed with handle angles of +30° and −15° respectively. The cycle sector had a significant effect on work (p < 0.001) and significantly (p = 0.002) higher work was performed in the pull down sector (25% higher than mean work over one cycle) as compared to the lift up sector (30% lower than mean work over one cycle). Therefore, a fixed handle angle of +30° is suggested to be optimal for power generation. The results of this study help to optimise the handbike–user interface. A more pronated handle angle compared to the one conventionally used was found to improve the performance of hand cycling and thereby the mobility of disabled people.

Optimal power allocation in server farms

Server farms today consume more than 1.5% of the total electricity in the U.S. at a cost of nearly $4.5 billion. Given the rising cost of energy, many industries are now seeking solutions for how to best make use of their available power. An important question which arises in this context is how to distribute available power among servers in a server farm so as to get maximum performance. By giving more power to a server, one can get higher server frequency (speed). Hence it is commonly believed that, for a given power budget, performance can be maximized by operating servers at their highest power levels. However, it is also conceivable that one might prefer to run servers at their lowest power levels, which allows more servers to be turned on for a given power budget. To fully understand the effect of power allocation on performance in a server farm with a fixed power budget, we introduce a queueing theoretic model, which allows us to predict the optimal power allocation in a variety of scenarios. Results are verified via extensive experiments on an IBM BladeCenter. We find that the optimal power allocation varies for different scenarios. In particular, it is not always optimal to run servers at their maximum power levels. There are scenarios where it might be optimal to run servers at their lowest power levels or at some intermediate power levels. Our analysis shows that the optimal power allocation is non-obvious and depends on many factors such as the power-to-frequency relationship in the processors, the arrival rate of jobs, the maximum server frequency, the lowest attainable server frequency and the server farm configuration. Furthermore, our theoretical model allows us to explore more general settings than we can implement, including arbitrarily large server farms and different power-to-frequency curves. Importantly, we show that the optimal power allocation can significantly improve server farm performance, by a factor of typically 1.4 and as much as a factor of 5 in some cases.

Concurrent dual-band SiGe HBT power amplifier for Wireless applications

This paper presents an investigation of a concurrent low-cost dual-band power amplifier (PA) fabricated in SiGe technology, able to simultaneously operate at two frequencies of 2.45 and 3.5-GHz, including an evaluation of its system level performance potentiality. Taking into account the technology novelty and the lack of device characterization and modeling, a hybrid (MIC) approach has been adopted both for a fast prototyping of the PA and for the evaluation of the device potentiality based on an extensive linear and nonlinear characterization. The comparison of PA performance in single-band or concurrent mode operation will be presented. In particular, the measured PA prototype shows an output power of 17.2 and 17-dBm at a 1-dB compression point, at 2.45 and 3.5-GHz, respectively, for CW single-mode operation, with a power added efficiency around 20%. System-level analysis predicts that, when the PA is operated under the 20-MHz Orthogonal Frequency-Division Multiplexing (OFDM) concurrent signals, the maximum output power levels to maintain the Error Vector Magnitude (EVM) within 5% are 11 and 3.5-dBm at 2.45 and 3.5-GHz, respectively. Moreover, new concepts and possible new system architectures for the development of the next generation of the multi-band transceiver front-end will be provided with an extensive system-level evaluation of the amplifier.

Measurements of the neutron spectrum energy in the IPEN/MB-01 reactor core

This work presents the results of neutron spectrum measurements at central position of the IPEN/MB-01 reactor core. For this purpose has been used several activation foils (Au, Sc, U, Mg, Ti, Ni, and In Foils) that have been irradiated at central position of the reactor core (standard rectangular configuration 28 × 26 fuel rods) in the maximum power level (100 watts). After this one the foils were counting at HPGe solid state detector (gamma spectrometry). The nuclear reaction rates experimental results (saturated activity per target nucleus) is together with an initial approach to the neutron reactor spectrum (estimated by reactor physics cellular codes) the main data to obtain the most appropriated neutron spectrum at the irradiation position by interactive adjustment process using the unfolding SANDBP code. The results obtained were (5.1312±0.1609).10(9) n/cm².s to the integral neutron flux, (9.8087±0.4974).10(8) n/cm² to the thermal neutron flux, (3.2272 ± 0.4378).10(9) n/cm².s to the intermediate neutron flux and (1.9040 ± 0.6390).10(9) n/cm².s to the fast neutron flux. These results are important and may be used to check and validate reactor physics codes and several nuclear data libraries.

SOLAR ENERGY DELIVERING GREENHOUSE WITH AN INTEGRATED NIR FILTER

The scope of this investigation is the design and development of a new type of greenhouse with an integrated filter for rejecting near infrared radiation (NIR) and a solar energy delivery system. Cooled greenhouses are an important issue to cope with the combination of high global radiation and high outdoor temperatures. As a first measure, the spectral selective cover material, which prevents the entrance of NIR radiation, is investigated. The special spectral selective properties of these materials have to block up to 50% of the solar energy outside the greenhouse, which will reduce the needed cooling capacity. The second measure is the integration of a solar energy system. When the NIR reflecting coating is designed as a parabolic or circular shaped reflector integrated in the greenhouse, the reflected solar energy of a PhotoVoltaic (PV) cell in the focus point delivers electric energy. With a ray tracing computer program the geometry of the reflector was optimally designed with respect to the maximum power level. The PV cells mounted in the focal point require cooling due to the high heat load of the concentrated radiation (concentration factor of 30-40). The properties of different materials, Ge, GaSb, CIS and Si cells were investigated to find the optimal cell for this application. All parts are integrated in a greenhouse structure with a size of about 100m2.

A 3~5 GHz UWB Up-Mixer Block Using 0.18-μm CMOS Technology

This paper presents a direct-conversion I/Q up-mixer block, which supports <TEX>$3{\sim}5$</TEX> GHz ultra-wideband(UWB) applications. It consists of a VI converter, a double-balanced mixer, a RF amplifier, and a differential-to-single signal converter. To achieve wideband characteristics over <TEX>$3{\sim}5$</TEX> GHz frequency range, the double-balanced mixer adopts a shunt-peaking load. The proposed RF amplifier can suppress unwanted common-mode input signals with high linearity. The proposed direct-conversion I/Q up-mixer block is implemented using <TEX>$0.18-{\mu}m$</TEX> CMOS technology. The measured results for three channels show a power gain of <TEX>$-2{\sim}-9$</TEX> dB with a gain flatness of 1dB, a maximum output power level of <TEX>$-7{\sim}-14.5$</TEX> dBm, and a output return loss of more than - 8.8 dB. The current consumption of the fabricated chip is 25.2 mA from a 1.8 V power supply.

A 0.13μm CMOS UWB RF Transmitter with an On-Chip T/R Switch

This paper presents a fully integrated 0.13 μm CMOS MB-OFDM UWB transmitter chain (mode 1). The proposed transmitter consists of a low-pass filter, a variable gain amplifier, a voltage-to-current converter, an I/Q up-mixer, a differential-to-single-ended converter, a driver amplifier, and a transmit/receive (T/R) switch. The proposed T/R switch shows an insertion loss of less than 1.5 dB and a Tx/Rx port isolation of more than 27 dB over a 3 GHz to 5 GHz frequency range. All RF/analog circuits have been designed to achieve high linearity and wide bandwidth. The proposed transmitter is implemented using IBM 0.13 μm CMOS technology. The fabricated transmitter shows a -3 dB bandwidth of 550 MHz at each sub-band center frequency with gain flatness less than 1.5 dB. It also shows a power gain of 0.5 dB, a maximum output power level of 0 dBm, and output IP3 of +9.3 dBm. It consumes a total of 54 mA from a 1.5 V supply.

Licensed to do anything [spectrum usage rights licensing

Licences broadly can either control the power transmitted or the interference caused. Controlling the transmitted power through a &apos;mask&apos; that defined the maximum power levels across a range of frequencies is only a weak control in the interference caused to neighbours. This is because were the licence holder to change the density of deployment of their base stations, perhaps as a result of changing the use that they put the spectrum to, then the interference suffered by the neighbour would increase despite the licence holder remaining within their mask. Significant changes in deployment, for example from a UMTS frequency division duplex (FDD) system to a WiMax time division duplex (TDD) system could have a very severe impact on neighbours even though it might appear that the transmitted power had decreased. So transmit restrictions, or &apos;block edge masks (BEMs)&apos; as they are coming to be known, are not the optimal way to control interference into neighbouring channels. Where such control of interference is important, a licence that specifies the maximum level of interference that could be caused, rather than the power that could be transmitted, is a superior way of licensing since it directly controls the problem. We call this form of licensing spectrum usage rights (SURs). SURs are generally better because they place only those restrictions on licence holders that are needed to protect neighbours, and no more. At the same time they provide certainty to neighbours as to the maximum levels of interference that they can expect, providing greater certainty for investors that the network they have paid to deploy will not suffer reduced capacity or need expensive re-engineering as a result of neighbours changing their usage. Determining the numbers to put into the licence terms requires an estimate of the likely transmit power, the likely base station density and some other factors such as I station antenna gain and height and the use of power control mechanisms. These can then be input to a propagation modelling tool which can be used to estimate the interference distribution and hence arrive at the SUR licence terms. The approach we follow is initially for Ofcom to make an estimate as to these parameters and then to consult on these.

Effects of short-term training using SmartCranks on cycle work distribution and power output during cycling

SmartCranks use a free running bearing to promote independent pedal work by each leg during cycling. This system is designed for training the upstroke phase during cycling. The effects of training with SmartCranks on the power output (PO) and on cycle work distribution at the anaerobic threshold and the maximum power level were examined. Twenty male, non-professional cyclists were randomly assigned into intervention and control group, training 5 weeks with SmartCranks and conventional cranks, respectively. Before and after the training period the subjects performed an incremental test to exhaustion. Lactate was measured to determine the individual anaerobic threshold (IAT) and forces at the pedal were recorded to quantify changes in the work distribution over the full revolution. We observed no significant statistical difference for peak power (PO; 333.3+/-32.8 W vs. 323.3+/-21.8 W) and PO at IAT (229.6+/-30.1 W vs. 222.7+/-25.2 W) for SmartCrank and control conditions, respectively (P>0.05). However, we did observe that work distribution in the downward phase was significantly reduced in the SmartCranks training group at peak PO (from 70.0+/-4.9% to 64.3+/-5.8%; P<0.05). Although the possible implications of the change in the work distribution of sectors are not known, for the success in cycling performance-indicated by the PO-training with the SmartCranks was not more advantageous than training with conventional bicycle cranks.

Effect of Irradiation Damage on the Deformation Properties of Zr-2.5Nb Pressure Tubes

Abstract The diametral expansion, elongation, and sag rates of Zr-2.5Nb pressure tubes in CANDU® (CANada Deuterium Uranium) nuclear reactors are important properties that limit their useful life and the maximum power level for reactor operation. As a result irradiation creep models are needed to predict the deformation behavior of the core components over the reactor life. It is important to know the creep behavior as a function of neutron flux in order to develop creep models over the range of operating conditions in the reactor core. At the edge of the reactor core, the neutron flux is decreasing very rapidly and there is a complex transition in creep behavior from irradiation-dominated creep to thermal-dominated creep. Also, mechanical properties such as tensile strength, fracture toughness, and delayed hydride-cracking are changing in the transition from thermal to irradiation conditions at the edge of the reactor core. Detailed studies have been completed on a Zr-2.5Nb tube irradiated in the NRU materials test reactor at Chalk River Laboratories. Pressure tube 601 was operating for a period of 66 950 h at temperatures ranging from about 547 K at the inlet and 571 K at the outlet. After the tube was removed in 1988 samples were taken for retrospective dosimetry to determine the fast neutron flux along the assembly. It was determined that the tube had been irradiated to a peak fluence of about 6×1025 n⋅m−2 corresponding to a fast neutron flux of about 2×1017 n⋅m−2⋅s−1. The flux profile was mapped and it was clear that the flux dropped rapidly to negligible values at about 0.5 m from the ends of the fueled zone. Samples of pressure tubes were taken for hardness testing and characterization by TEM and XRD analysis at various locations corresponding with different operating conditions (neutron flux and temperature) but at the same time. The creep behavior during operation was obtained by periodic gaging of the pressure tube internal diameter. The results of the microstructure characterization are presented and discussed in relation to the measured mechanical properties (creep and hardness). The microstructure and mechanical properties change significantly in the transition from the unirradiated state up to fluxes of about 1×1017 n⋅m−2⋅s−1.

A Multimode Transmitter in 0.13 $\mu\hbox{m}$ CMOS Using Direct-Digital RF Modulator

This paper presents a system-independent transmitter architecture based on a direct-digital RF-modulator which combines the D/A conversion, up-conversion, unwanted sideband rejection, power control, and part of the digital image-rejection filtering into a single mixed-signal circuit block. The multimode capability of the architecture is demonstrated with WCDMA, EDGE, and WLAN system requirements. The modulator achieves 90 dB of power control range and with an external power amplifier module, WCDMA EVM of less than 2% from signal powers of -20 dBm to +25 dBm. The noise floor level defined by the quantization noise at 190 MHz offset from the carrier is -150 dBc/Hz measured at the output of the PA with +25 dBm signal power. The analog power consumption with the maximum signal power level is 92 mW and scales down to 46 mW when reducing the signal level to -43 dBFS. The digital power consumption is 65 mW. The chip is implemented with a standard 0.13 mum 1.2 V digital CMOS with total silicon area of 4 mm2.

High-Power Short-Pulse, Mechanical, and Thermohydraulic Tests of the Window Prototype for Remote Steering Launcher

The millimeter-wave system of the remote steering launcher at the upper port level is composed of beamlines that are rated for 2-MW continuous-wave operation at 170 GHz. In each beamline, a torus window is located between the entrance to the in-vessel square corrugated waveguide and the steerable mirrors in the launcher back end. In the reference design, the maximum steering angle of 12 deg imposes a 27-mm off-center beam shift to the window disk center, which in turn leads to asymmetrical heating of the window. This raises particular concerns of enhanced thermomechanical stresses in the window and in the metallic window cuffs. In order to qualify the optical, mechanical, and thermohydraulic design, high-power short-pulse and thermohydraulic tests were performed using a prototype chemical vapor deposition diamond torus window developed and manufactured at Forschungszentrum Karlsruhe. It was proven that arcing did not occur even under maximum millimeter-wave power levels available (up to 0.53 MW) and that the millimeter-wave beam profile was fully maintained. A test facility allowed thermohydraulic studies of the window cooling system with parameters characteristic for component cooling water loops at ITER (pw = 1.0 MPa, Tw = 40°C).