4,714 research outputs found
The South African Phillips Curve: How Applicable is the Gordon Model?
No full textIs there a Phillips curve relationship present in South Africa and if so, what form does it take? Traditionally the way to estimate the Phillips curve is merely to regress the change in the price level on a measure of the output gap (or the deviation of actual unemployment from the NAIRU). However, Gordon (1990:481-5) has argued that estimating the Phillips curve in this manner biases the estimated results. Instead, Gordon (1997; 1989) puts forward his so-called triangular model that controls for inertia effects, output level effects and rates-of-change (in output) effects. He applies the model to several European countries, the US and Japan and finds meaningful results. The question this paper poses is whether or not the triangular model also applies to South Africa. In estimating the Phillips curve for South Africa the paper also experiments with four versions of the output gap, based on four different methods to estimate long run output, including the standard Hodrick-Prescott (HP) filter and the production function approach. There are several variants of the Phillips curve. The first, as estimated by Phillips (1958) himself, measures the relationship between wage inflation and unemployment. However, other versions consider the relationship between price inflation and unemployment or price inflation and output. This paper focuses on the latter, given the absence of quarterly unemployment data in South Africa, as well as the lack of a reliable and sufficiently long unemployment time series. The paper first presents an overview of literature on the Phillips curve and its estimation for South Africa and other countries. This is followed by the second section that considers the model to be estimated, the data as well as the discussion of the alternative measures of the output gap. The third section presents the estimated results followed by section four that contains the conclusion and a discussion of the policy implications.
The Real-time Forecasting Performance of Phillips Curves
No full textAnalysts typically use a variety of techniques to forecast inflation. These include both ‘bottom-up’ approaches, for near-term forecasting, as well as econometric methods (such as mark-up models of inflation, which have been found to perform quite well for Australia – see de Brouwer and Ericsson (1998)). One of the econometric approaches to inflation forecasting which is sometimes considered is the use of Phillips curves based on estimates of the output gap. This paper suggests, however, that the real-time capacity of such Phillips curves to forecast inflation is limited, relative even to such simple benchmark forecasting approaches as an autoregressive (AR) model of inflation or a random walk assumption. It appears that the lack of precision with which output-gap-based Phillips curves can be estimated in real time limits their usefulness as a means of forecasting inflation in isolation. Phillips curve-based forecasts may, however, perform a little better than AR model-based ones in at least predicting whether inflation will increase or decrease from its current level. Moreover, combining Phillips curve-based forecasts with those from simple, alternative approaches does seem to offer some scope for improving the real-time forecast accuracy of the latter. These observations suggest that, in spite of their generally disappointing performance as a means of forecasting inflation in isolation, output-gap-based Phillips curves may continue to be useful in real time – as a tool for conditioning gap estimates within a multivariate filtering framework, and as a possible complement to other, alternative inflation forecasting approaches.monetary policy; forecasting inflation; output gaps; real-time data
High-resolution spectroscopy (XPS, 1^H MAS solid-state NMR) and DFT investigations into Ti-modified Phillips CrO_x/SiO_2 catalysts
No full textTi-modified Phillips catalyst is a most important industrial catalyst widely used in ethylene polymerization, but the mechanism still remains mysterious. In this work, Ti-modified Phillips catalysts were characterized by high-resolution X-ray photoelectron spectroscopy (XPS) and 1^H magic-angle-spin solid-state nuclear magnetic resonance (1^H MAS solid-state NMR) combined with density functional investigations on the effects of Ti-modification on promotion of polymerization activity, and regulation of microstructures of the polymer chains. XPS data revealed Ti-modification caused increase of electron-deficiency and photo-stability of the surface chromate species. 1^H NMR provided the first direct evidence of surface residual Ti–OH groups. Modeling results rationalized well the effects of Ti-modification on promotion of polymerization activity, extension of molecular weight distribution (MWD) to lower MW region, improvement of the distribution of inserted co-monomer and enhancement of 2,1-insertion in regioselectivity of Phillips catalysts. It was the first time the Ti-modification on Phillips catalysts were theoretically elucidated
Comparative feasibility study of a 30 MW disruptive floater solution with a 15 MW PivotBuoy and a benchmark 15 MW semi-submersible floater in the Bay of Biscay
No full textThis paper investigates the technical, life cycle, and economic feasibility of a 30 MW upscaled downwind turbine, comparing it to a 15 MW X1 Wind PivotBuoy downwind turbine and a benchmark 15 MW IEA Umaine VolturnUS-S upwind turbine in the 450 MW Sud de la Bretagne I wind farm site. The study is significant due to the rising energy demand, the potential for decreasing the levelized cost of energy with increased turbine size, and the optimized use of space. The size limit of current upwind turbine designs could be addressed using a downwind turbine solution.The research is conducted by modelling the global dynamic response of the structure using OpenFAST and computing the natural frequencies and stresses using a finite element model. A lifecycle analysis is performed to identify potential pitfalls and bottlenecks by analysing the individual lifecycle phases. The economic feasibility is assessed by simulating the annual energy production using TOPFARM and utilizing structural analysis and lifecycle assessment to quantify capital, operational, and abandonment expenditures. Based on the annual energy production and the performance indicators the levelized cost of energy is calculated.The findings indicate that while the global stability is within boundaries, the stress in members is too high with a simple scale-up of the proposed design. Bottlenecks are found in lifting operations and supply chain readiness. The levelized cost of energy and capital expenditure increased due to substructure self-weight, rendering the proposed 30 MW scale-up currently unfeasible when compared to the other two wind farms.These findings are important as they demonstrate that the 15 MW X1 Wind PivotBuoy is not scalable without design changes. The levelized cost of energy does not decrease with an increased floater solution. The 15 MW X1 Wind PivotBuoy downwind turbine seems more economically viable, making it a more interesting option for future development.Civil Engineerin
Repopulation of a coastal stream by brook trout and rainbow-trout after endosulfan poisoning
No full textPT: J; CR: BERGER BL, CITED INDIRECTLY GUNNING GE, 1968, PROG FISH CULT, V30, P92 OLMSTED LL, 1974, T AM FISH SOC, V103, P79 PETERSON RH, 1975, J FISH RES BOARD CAN, V31, P1757 PHILLIPS WEJ, 1965, ENDOSULFAN ITS EFFEC PHILLIPS WEJ, 1975, 14098 NAT RES COUNC RICKER WE, 1968, IBP3 INT BIOL PROGR SCHOETTGER RA, 1970, BUR SPORT FISH WILDL, V35, P1 SMITH MW, 1958, J FISH RES BOARD CAN, V15, P1403 SMITH MW, 1963, J FISH RES BOARD CAN, V20, P327; NR: 10; TC: 3; J9: PROGR FISH-CULT; PG: 4; GA: JS849Source type: Electronic(1
The Validity of the Phillips Curve Relationship: An Econometric Study on Moroccan Data
No full textThe Phillips curve is a key tool in the formulation of economic policies. The primary objective of this study is to examine the validity of this curve in the Moroccan context. To this end, we employ an ARDL model, applied to annual data covering the period from 1991 to 2023. The results reveal a co-integration relationship, indicating a stable and long-term link between inflation and unemployment. However, contrary to the classical predictions of the Phillips curve, the analysis shows a significant positive impact of inflation on unemployment: a 1% increase in unemployment leads to a 1.22% rise in inflation in the short term, and 1.51% in the long term. These findings challenge the applicability of the Phillips curve in Morocco, highlighting that local economic dynamics deviate from the traditional trade-off between inflation and unemployment. This divergence underscores the urgent need to redefine Morocco's economic policies by adopting integrated and balanced monetary and fiscal strategies to effectively address these two major challenges
Short-circuit characteristics of superconducting permanent magnet generators for 10 MW wind turbines
No full textSuperconducting permanent magnet generators (SCPMGs) are a potential candidate for 10 MW direct-drive wind turbine applications. This paper presents two 10 MW SCPMG designs using MgB<sub>2</sub> cables for the armature winding and investigates the short-circuit characteristics of the designed SCPMGs. The first part of the results shows that the SCPMGs can double the shear stress of a conventional low-speed permanent magnet (PM) generator (from 65 kPa to 130 kPa) whilst avoiding demagnetization of the PMs in rated-load operation. However, the power factor has to drop to a range of 0.7-0.8. The second part of the results shows that during a sudden three-phase short circuit, the superconducting armature winding is prone to quench and the PMs are likely to be demagnetized in both proposed designs.Accepted Author ManuscriptTransport Engineering and Logistic
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Economic Study of Geothermal Steam Production and Power Generation
No full textThis report presents the results of the study to determine the required selling price of geothermal flash steam in order for Phillips Petroleum Company to obtain a rate of return on investment of 10, 15 or 20% on its discovery in Nevada. The economic evaluations are based on an order-of-magnitude type of estimate of capital costs for the flash steam production, steam gathering and brine reinjection system to supply steam to a 55 MW (Gross) geothermal power generating plant, using mixed pressure (double flash steam) and turbine design. Geothermal well costs, brine quality and well productivity data were provided by Phillips Petroleum Company and are based on the discovery wells in Nevada. Power plant costs are based on current technology and available hardware, under construction at the present time. Costs have been escalated to 1977
An Ultrasonically Powered System Using an AlN PMUT Receiver for Delivering Instantaneous mW-Range DC Power to Biomedical Implants
No full textAluminum Nitride (AlN) Piezoelectric Micromachined Ultrasonic Transducers (PMUTs) are gaining interest for biomedical implant power due to biocompatibility and lowtemperature processing. However, due to the low piezoelectric coefficient of AlN PMUTs, storage capacitors are often used to accumulate ultrasonic power transferred over an extended time. The accumulated energy is then used to power a DC load, which leads to a long start-up time, and insufficient duty cycle for some applications. We present an ultrasonically powered system for biomedical implants capable of delivering mW-range instantaneous power to DC loads, without pre-storing it. The system features a 25 mm2 AlN PMUT, an inductive matching network, and an application-specific power management integrated circuit(ASIC). For an acoustic intensity of 360 mW/cm2 at the surface of the PMUT, an open-circuit voltage of 1.11 V and an aperture efficiency of 30.5 % are measured. Furthermore, by connecting a series-matching inductor to the PMUT, the highest-reported power delivered to the load (PDL) of 6.4 mW is measured over an optimal load of 7.6 Ω. Finally, together with the ASIC and at the intensity of 108 mW/cm2, our system delivers 1.04 mW DC power to a 3.3 kΩ load, which is over two orders of magnitude higher than the previously reported average DC power for AlN PMUTs.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Bio-ElectronicsElectronic Components, Technology and Material
Inversion of coseismic deformation due to the 8th February 2016, Mw 4.2 earthquake at Los Humeros (Mexico) inferred from DInSAR
No full textOn the 8th of February 2016, a Mw 4.2 earthquake was detected inside the Los Humeros caldera, located in the eastern sector of the Trans-Mexican Volcanic Belt. The event occurred after a sharp increase in the injection rate at the Los Humeros Geothermal Field and it was recorded by the seismic monitoring network of the power plant. The earthquake was felt by the local population and it caused damage in the power plant infrastructure. The focal mechanism solution of a previous study based on seismological data shows a reverse movement with a minor left-lateral component: Mw=4.2, depth=1500m, strike=169°, dip=61°, rake=42°. We have performed a geodetic and geomechanical analysis of the seismic source event based on ground deformation inferred from DInSAR. We used ascending and descending Sentinel-1 differential interferograms to retrieve the horizontal and vertical components of the co-seismic deformation. Subsequently, we inverted the estimated deformation to obtain the solution of an activated fault using the Okada model. These results shed light on the geomechanical aspects of the event and can help to understand the effects of field operations interacting with pre-existing structural features and active tectonic processes in the Los Humeros caldera.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Mathematical Geodesy and Positionin
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