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The aim of the paper is to establish the COst-Specific Air Range (COSAR) as a new figure-of-merit based on the cost of energy to optimise the flight profile of a hybrid energy aircraft.

After reviewing the expression and the application of the specific air range (SAR) and of the energy-specific air range (ESAR), the need of a new figure-of-merit for flight technique optimisation of hybrid energy aircraft is motivated. Based on the specific cost of the energies consumed, the mathematical expression of COSAR is derived. To enable optimum economics operations, a cost index (CI) derivation is introduced for a variety of hybrid-electric concepts to consider the additional time-related cost. The application of COSAR and of the CI is demonstrated for cruise optimisation of a hybrid-electric retrofit aircraft concept.

As a consequence of the consumption of multiple energy sources in a hybrid aircraft, optimisation according to the objective functions SAR and ESAR leads to minimum in-flight CO2 emissions and minimum energy consumption for a given stage length. While the optimisation of a single energy source aircraft according to these figures-of-merit directly results in minimum energy cost for a given unit range, this statement is no longer true for hybrid-energy aircraft. Consequently, introducing a new figure-of-merit established on the specific cost of the energies consumed enables flight technique optimisation for minimum energy cost of hybrid-energy aircraft. Additionally, the related time-cost is taken into account by means of a CI definition for minimum operating cost.

COSAR may serve as an alternative to SAR used today as the standard figure-of-merit for fuel optimised flight profile. Using COSAR and the CI allow airlines to adapt the flight profiles of hybrid-energy aircraft fleets according to the energy market price and their related cost of time to determine optimum economical flight profile.

Using COSAR as a figure-of-merit, the flight profile of hybrid energy aircraft can be optimised for minimum energy cost. Time-related costs are considered for optimum operating economics by utilisation of the CI definition for hybrid energy aircraft.

THE increasing speed of modern aircraft has brought to the forefront the necessity for making a careful drag analysis of all aircraft in order to separate out the essential drag, that is to say the drag that is unavoidable, from the non‐essential drag. Most designers, we believe, now do this in order to see what progress is being made in the streamlining of their products. By this means we are enabled to see the relative importance of the drag terms and to arrive at a figure of merit. The ideally‐streamline aeroplane, though not at present a precise proposition, is like other ideals unattainable. It is the standard to which designers may aspire, but which they cannot achieve.

To demonstrate the improvement of three‐axial magnetic sensors systems for magnetocardiography when using minimum norm solutions (MNS).

The thesis is proved by using figures of merit and by means of repeated numerical simulations, starting from a BEM model for forward calculations.

We found out that both for under‐determined and over‐determined problems two figures of merit show better performance of a three‐axial sensor system when compared with two mono‐axial sensor systems. We also showed the positive impact of three component magnetic field data on MNS by means of repeated simulations.

The analysis is limited to theoretical sensor systems and can be applied also to realistic measurement set‐ups. Noise is considered uncorrelated. The analysis could be carried out with the help of other figures of merit. More refined models for the human body could be adopted.

The use of three axial sensor systems is encouraged in the field of magnetocardiography.

Numerical analysis of inversion algorithms using three‐dimensional magnetic field data in magnetocardiography have been never carried out.

The aim of this study was to first establish foundational algebraic expressions that parametrically describe any advanced dual-energy storage–propulsion–power system (DESPPS) and then proceed to declare the array of fundamental independent variables necessary for the sizing and optimisation of such systems. Upon procurement of a pre-design-level integrated aircraft performance model and the subsequent verification against previously published high-end low-fidelity generated results, opportunity was taken in formulating a set of battery-based DESPPS related design axioms and sizing heuristics.

Derivation of algebraic expressions related to describing DESPPS architectures are based on first principles. Integrated performance modelling by way of full analytical fractional change transformations anchored according to a previously published Energy Specific Air Range (ESAR) figure-of-merit originally derived using the Breguet–Coffin differential equation for vehicular efficiency. Weights prediction of sub-systems that constitute the entire aircraft including DESPPS constituents emphasises an analytical foundation with minimal implementation of linear correlation factors or coefficients of proportionality. An iterative maximum take-off weight build-up algorithm emphasising expedient and stable convergence was fashioned. All prediction methods pertaining to integrated performance were verified according to previously published battery-based DESPPS results utilising high-end low-fidelity methods.

For all types of DESPPS, two new fundamental independent non-dimensional variables were declared: the Supplied Power Ratio (related to converted power afforded by each energy carrier); and, the Activation Ratio (describing the relative nature of utilisation with respect to time afforded by the motive power device associated with each energy source). For a given set of standalone sub-system energy conversion efficiencies, the parametric descriptor of degree-of-hybridisation (DoH) for Power was found to be solely a function of the Supplied Power Ratio, whereas in contrast, the DoH for Energy was found to be a more complex synthetic function described by comingling of Supplied Power Ratio and the Activation Ratio. Upon examination of the integrated aircraft performance model derived in this treatise, for purposes of investigating CO₂-emissions reduction potential for battery-based DESPPS using kerosene as one of the energy sources, one salient observation was maximising the ESAR figure-of-merit is not an appropriate objective or intermediary function for future optimisation work. It was found maximising block fuel reduction through the use of maximum ESAR would lead to ever diminishing design ranges and curtailment of the payload-range working capacity of the aircraft.

Opportunity is now given to design and optimise aircraft utilising any type of DESPPS architecture. It was established that designing for battery-based DESPPS aircraft can be achieved effectively in a two-stage process that may not require aircraft morphologies more exotic than the so-called “wing-and-tube”. Firstly, a suitably projected state-of-the-art aircraft with solely advanced gas-turbine technology for the propulsion and power system needs to be produced. Thereafter, a revised version of this baseline projected aircraft now using DESPPS architecture should be conceived. A recommendation related to CO₂-emissions reduction potential for battery-based DESPPS using kerosene as one of the energy sources is that during optimisation work the multi-objective formulation should comprise at least two functions: block fuel and operating economics. In all instances, it was advised that the objective function of block fuel should be tempered by an equality constraint of ESAR parity with the baseline projected aircraft using gas-turbine only technology.

A complete, unified analytical description of DESPPS that is universally applicable to any type of energy carrier has been derived and verified for battery-based dual-energy systems. Correspondingly, a set of aircraft design axioms and sizing heuristics relevant to battery-based DESPPS have been presented.

The purpose of this paper is to design a low phase noise and high figure of merit, fully integrated, voltage‐controlled oscillator (VCO) which was fabricated in TSMC CMOS 0.18‐μm 1P6M process.

A differential PMOS cross‐coupled architecture VCO with the capacitive feedback technology was designed to increase the linearity of frequency tuning range and decrease the phase noise. Varactor determining the performance of tuning range is also a key component in the design of VCO. The authors adopt the accumulation‐mode MOS varactor. The output spectrum and the phase noise are measured by E5052A spectrum analyzer.

The VCO is successfully fabricated in TSMC RF CMOS 0.18um 1P6M process. The measured tuning range is from 10.875 GHz ∼ 11.1 GHz with control voltage from 0 to 1.5 V. The measured phase noise is as low as −120.42 dBc/Hz at 1 MHz offset and the high FOM is −189.5 dBc/Hz. The output spectrum is −10.51dBm with center oscillator frequency of 10.942 GHz. The core circuit without buffer consumes power of 15 mW from a 1.8 V supply voltage.

This paper shows a fully integrated CMOS LCVCO architecture using capacitive feedback technology with low phase noise and high figure of merit for OC‐192 SONET applications.

In early 1989 the original version of the Reliability Figures of Merit (FM) for the solder attachments of surface mount (SM) assemblies was published. That version of the FM was specifically tailored for telecommunications environments. Misapplications of FMs to use environments, such as military applications and accelerated tests, pointed to a real need for generally applicable FMs. Adequate reliability of SM solder connections can only be assured with a ‘Design for Reliability’ based on solder joint behaviour and the underlying fatigue damage mechanisms. Perceived difficulties with a ‘Design for Reliability’ stem from the very complex and only partially understood nature of the interacting mechanisms underlying thermally induced solder joint fatigue, combined with the highly temperature, time, and stress‐dependent behaviour of some of the materials involved, especially solder. In this paper generic FMs are presented. These are simple design tools, easily applied by users unfamiliar with the underlying complexities of solder fatigue and the reliability assessment results are in Go/No‐go format. The oversimplifications contained in Version 1 of the FMs (originally thought necessary for simple design tools and limiting their applicability) are omitted, making these generic FMs more readily understood.

Multiphase and quadrature voltage-controlled oscillators (QVCOs) play key roles in modern communication systems and their phase noise performance affects the performance of the overall system. Different studies are devoted to efficient quadrature signals generation. This paper aims to present a new low-phase noise superharmonic injection-locked QVCO.

The proposed QVCO is comprised of two identical inductor-capacitor circuit (LC)-voltage-controlled oscillators (VCOs) in which second harmonics, with 180° phase shift, are injected from one core VCO to the gate of tail current source of the other VCO via a coupling capacitor. Using second harmonics with high amplitude will switch the tail from the inversion to the accumulation, and therefore, flicker noise is reduced. Also, because of the use of lossless and noiseless coupling elements, that is, coupling capacitors, and also because of the existence of an inherent high-pass filter, the proposed LC-QVCO has a good phase noise performance.

The introduced technique is designed and simulated in a commercial 0.18 µm radio frequency complementary metal oxide semiconductor (RF-CMOS) technology and 10 dB improvement of close-in phase noise is achieved (compared to the conventional method). Simulation results show that the phase noise of the proposed QVCO is −130.3 dBc/Hz at 3 MHz offset from 5.76 GHz center frequency, while the total direct current (DC) current drawn from a 0.9-V power supply is 4.25 mA (figure of merit = −190.2 dBc). Monte Carlo simulation results show that the figure of merit of the circuit has a Gaussian distribution with mean value and standard deviation of −189.97 dBc and 0.183, respectively.

This technique provides a new simple but efficient superharmonic coupling and noise shaping method that reduces close-in phase noise of superharmonic multiphase VCOs by switching of tail transistors with 2 ω0 (second harmonic of oscillation frequency). No extra devices such as area-consuming transformer or additional power-hungry oscillator are used for coupling.

This paper aims to correlate the flexible multibody analysis for the performance, blade airloads, rotor pitch control angles, and blade structural loads of a full-scale utility helicopter rotor in low-speed forward flight with wind tunnel test and flight test data.

A nonlinear flexible multibody dynamics analysis code, DYMORE, is used to analyze the performance and aeromechanics of a utility helicopter rotor in low-speed forward flight. The main rotor system is modeled using various multibody elements such as rigid bodies, nonlinear elastic beams, mechanical joints, and elastic springs/dampers. The freewake model is used to capture rotor wakes more elaborately in low-speed forward flight.

Fair to good correlations of rotor performance such as figure of merit in hover, rotor power, propulsive force, and lift in low-speed forward flight are achieved with sweeps of the thrust, rotor shaft tilting angle, and advance ratio, against wind tunnel test data. The blade section normal forces from the mid-span to outboard are fairly or well correlated with flight test data, but the normal force at the inboard blade station is under-predicted. The trimmed pitch control angles are reasonably predicted; however, the lateral cyclic pitch control angle is moderately under-predicted. The flap bending moments are compared fairly with measurements; however, the oscillations of the lead-lag bending and torsion moments are not captured well.

Reasonable predictions of the performance and aeromechanics of the rotor in low-speed forward flight will allow the flexible multibody dynamics to be used for the rotorcraft comprehensive analysis, in place of expensive flight and wind tunnel tests of the rotor.

Up to now, the stand-alone flexible multibody dynamics without the aid of external aerodynamic analysis has not been widely used for the analyses of rotor performance and aeromechanics in low-speed forward flight. However, the present flexible multibody dynamics analysis directly integrated with the freewake model gives fair to good correlation of the rotor performance and aeromechanics predictions in low-speed forward flight.

This paper aims to report small-signal parameter extraction and simulation of enhanced dual-channel dual-material gate AlGaN/GaN high electron mobility transistor (HEMT) for the first time for the characterization of a device in microwave range of frequency.

For parameter extraction, a standard and well-known direct parameter extraction methodology is applied. Extrinsic elements of small-signal circuit model are extracted from measured S-parameters obtained using pinch-off cold field effect transistor (FET) biasing in the first step at a low frequency range and at a higher frequency range in the second step to ensure higher extraction accuracy. Intrinsic elements are extracted from intrinsic Y-parameters that are obtained after de-embedding all the extrinsic parasitic elements of the device. Figure of merits of radio frequency are also derived from the measured results and S-parameters of the proposed device.

Small signal parameters of the proposed device circuit model are extracted using the standard direct parameter extraction technique. Analysis of microwave figure of merits for device include maximum oscillation frequency, cut-off frequency, current gain, transducer power gain, available power gain, maximum stable gain, transconductance, drain conductance, stern stability factor and time delay.

The paper bridges the gaps between theory and experimental practices by validating extracted results with reported results of structurally matching devices.

An enhanced device structure investigated for small signal parameters incorporates field plate over dual metal engineered gate to provide better electric field uniformity, effective suppression of short channel effect, reduction in current collapse, improvement in carrier transport efficiency and enhancement in drain current capabilities.

The study aims to present the hybrid approach of multiple MCDM techniques with strategic perspective to assist the vendor ranking process.

Multiple MCDM techniques such as fuzzy QFD, mathematical modelling and ANP (analytical network process) are integrated in the model for vendor ranking. Multiple phases in vendor ranking such as pre‐qualification and final selection are dealt with using the above techniques.

Compared to individual approaches, the proposed hybrid model effectively assists the vendor ranking process. The efficacy of the proposed approach is evident from the case study of an automotive components manufacturer involving 20 vendors comprising pre‐qualification by fuzzy QFD and final selection by ANP. This set of potential vendors is evaluated based on three main criteria and eight sub criteria.

Fuzzy QFD is employed for qualifying supplier to form a supplier pool, as it is helpful in converting qualitative information into quantitative parameters. This data is then combined with other quantitative data to form a mathematical model. The mathematical model is solved by the method of integer programming, using TORA. ANP with BOCR (benefits, opportunities, costs, and risks) is proposed for evaluating and selecting appropriate supplier. ANP model is solved using Super Decision package.