Browsing by Subject "inflation"

The purpose of this thesis was to design, build and test a system, which is capable of measuring in real time simple quantities influencing on tire-soil contact of agricultural tractors mobility. The measuring equipment is based on acceleration and distance sensors connected to the Arduino Uno microcontroller. The tractor’s CAN bus was logged and the data was saved using a CAN bus card connected to a Raspberry Pi minicomputer. The sensors were calibrated, and their sensitivity checked before performing the experiments while driving in the field. Accelerometers were placed on top of the rear axle of the tractor at both ends in housings printed for them and distance sensors were mounted behind the rear axle. All sensors were logged by using Raspberry's Raspbian operating system with a python program. The Raspberry was chosen as a computer because of its demanding low space, low cost, and versatility of interfaces. The properties of the field were monitored by monthly penetrometer measurements as well as SoilScout sensors embedded in the ground, which indicated the moisture and temperature of the ground at that depth in real time. The purpose of this was to find out the changes in the field during the growing season, which would also affect the tractor's mobility. The measurement were carried out successfully and the result were considered to be reliable and provide many other opportunities for the future. The results clearly indicated the factors influencing the tractor’s mobility and the different stages of the tillage could be recognized. Future challenges remain the filtering of large amounts of data and the application of measuring equipment in further research. The measurement equipment developed in the work is well suited for its purpose in terms of measurement accuracy and economical affordability. In the future, better accuracy could be achieved with more accurate measuring devices as well as data obtained from this work.

This study examines the cyclicality of discretionary fiscal policy in Vietnam using annual time series from 1990 to 2015. The change in cyclically adjusted balance (fiscal impulse) is utilized as the indicator of active fiscal action, while the output gap as the proxy for business cycle. Evidence shows discretionary fiscal policy follows a procyclical trend over business cycles, but reversed since 2008. In addition, discretionary fiscal policy is more procyclical during recessions than in booms. Finally, discretionary fiscal policy tends to react to inflation in a stabilizing way, i.e., contractive after inflation surges and expansive after inflation dives. This suggests that Vietnam has been using discretionary fiscal policy to stabilize general price level rather than output cycles.

We study how higher-order gravity affects Higgs inflation in the Palatini formulation. We first review the metric and Palatini formulations in comparative manner and discuss their differences. Next cosmic inflation driven by a scalar field and inflationary observables are discussed. After this we review the Higgs inflation and compute the inflationary observables both in the metric and Palatini formulations. We then consider adding higher-order terms of the curvature to the action. We derive the equations of motion for the most general action quadratic in the curvature that does not violate parity in both the metric and Palatini formulations. Finally we present a new result. We analyse Higgs inflation in the Palatini formulation with higher-order curvature terms. We consider a simplified scenario where only terms constructed from the symmetric part of the Ricci tensor are added to the action. This implies that there are no new gravitational degrees of freedom, which makes the analysis easier. As a new result we found out that the scalar perturbation spectrum is unchanged, but the tensor perturbation spectrum is suppressed by the higher-order curvature couplings.

I use hydrodynamic cosmological N-body simulations to study the effect that a secondary period of inflation, driven by a spectator field, would have on the Local Group substructures. Simulations of the Local Group have been widely adopted for studying the nonlinear structure formation on small scales. This is essentially because detailed observations of faint dwarf galaxies are mostly limited to within the Local Group and its immediate surroundings. In particular, the ∼ 100 dwarf galaxies, discovered out to a radius of 3 Mpc from the Sun, constitute a sample that has the potential to discriminate between different cosmological models on small scales, when compared to simulations. The two-period inflaton-curvaton inflation model is one such example, since it gives rise to a small-scale cut-off in the ΛCDM primordial power spectrum, compared to the power spectrum of the ΛCDM model with single field power-law inflation. I investigate the substructures that form in a simulated analogue of the Local Group, with initial conditions that incorporate such a modified power spectrum. The most striking deviation, from the standard power-law inflation, is the reduction of the total number of subhalos, with v_max > 10 km/s, by a factor of ∼ 10 for isolated subhalos and by a factor of ∼ 6 for satellites. However, the reduction is mostly in the number of non-star-forming subhalos, and the studied model thus remains a viable candidate, taking into account the uncertainty in the Local Group total mass estimate. The formation of the first galaxies is also delayed, and the central densities of galaxies with v_max < 50 km/s are lowered: their circular velocities at 1 kpc from the centre are decreased and the radii of maximum circular velocity are increased. As for the stellar mass-metallicity and the stellar mass-halo mass relations, or the selection effects from tidal disruption, I find no significant differences between the models.

The aim of this thesis is to study how the exogenous oil supply shocks generate the U.S. inflation. Exogenous oil supply shocks are determined to be political and military crises that are non-market based and affect the level of the oil supply. According to the economic theory, crises in the oil production regions cause a shortfall in the oil supply. The declined supply will raise the price of oil and therefore boost the inflation. The analyses are based on the time period of 1973 – 2016. This thesis measures the magnitude of the exogenous oil supply shocks by two methods. The first method creates a counterfactual oil production path that estimates the production that would have occurred in the absence of the shock. Comparing the actual and counterfactual production path gives an estimate for the magnitude of the shock. The second method uses the structural vector autoregression model to estimate the magnitude of the shocks. The relationship between the exogenous oil supply shocks and inflation is studied by two different methods. The autoregressive distributed lag model is constructed to see how the inflation is affected by the lags of the oil supply shocks time series and inflation. The second model is based on the structural vector autoregression model where the oil supply shocks are conducted. The impulse responses are estimated by a regression model to understand how exogenous oil supply shocks generate inflation. Both models allow the construction of the structural brake analysis. The aim of the structural brake analysis is to understand how the relationship between inflation and oil supply shocks has evolved over time. The structural brake analysis implies that the models in general give misleading results. The time period must be separated to four different subperiods in order to get adequate models. The results imply that the relationship between the oil supply shocks and inflation has changed over time. In the first period from early 1970’s to early 1980’s, the exogenous oil supply shocks had statistically significant effect on inflation. In the second and third periods from 1980’s to 2000’s, models do not find significant effect. The models give contradictory results for the fourth period in the 2010’s. The autoregressive distributed lag model does not find statistically significant effect from the exogenous oil supply shocks at inflation where impulse response analysis does. The main contributions of this thesis to the preceding literature can be divided into two sections. Firstly, the structural brake analysis has not been constructed in this field. The results give a useful insight how the relationship has evaluated over time and helps to understand the intertemporal variation of the effects. Secondly, this thesis extends the analysis to the end of 2016.

The role of central banks has increased in the past years, especially during the recovery from the COVID-19 pandemic, but their main policy goal also remains focused on maintaining price stability. However, this goal has become problematic as inflation exceeds their 2 percent target. The zero lower bound has initiated the adoption of unconventional methods, such as quantitative easing, to influence policy. Quantitative easing operates through various transmission channels, one of which is the portfolio rebalancing channel. In this channel, investors must rebalance their portfolios due to central banks purchasing government bonds, prompting the search for substitutes. This process leads to an increase in the price of all assets, creating a wealth effect. This thesis aims to investigate the role of the wealth effect as an inflation driver. Structural vector autoregressive models have become the backbone of monetary policy analysis. However, the shock of interest must be identified by imposing restrictions on the model. In this thesis, sign and narrative sign restrictions were used. Traditional sign restrictions alone were not an option due to the variable dynamics. The empirical application of this thesis was based on Bayesian estimation, assuming non-Gaussian error terms. In the Bayesian estimation, a Differential Evolution Markov Chain algorithm was utilized. The results of the empirical application yielded somewhat controversial findings. On one hand, unconventional monetary policy did contribute to the wealth effect. On the other hand, the wealth effect did not contribute to inflation. Interestingly, the impulse response functions did not show a significant impact of the unconventional monetary policy shock itself, which contradicts the findings of previous literature. The impulse response functions of the entire model revealed the existence of more powerful inflation drivers in the economy, indicating potential topics for future research. Additionally, the results varied when considering different time periods, suggesting changes in the dynamics of the economy.