Satellite clock time offset prediction in global navigation satellite systems

In an operational sense, satellite clock time offset prediction (SCTOP) is a fundamental requirement in global navigation satellite systems (GNSS) tech- nology. SCTOP uncertainty is a significant component of the uncertainty budget of the basic GNSS pseudorange measurements used in standard (i.e not high-precision), single-receiver applications. In real-time, this prediction uncertainty contributes directly to GNSS-based positioning, navigation and timing (PNT) uncertainty. In short, GNSS performance in intrinsically linked to satellite clock predictability. Now, satellite clock predictability is affected by two factors: (i) the clock itself (i.e. the oscillator, the frequency standard etc.) and (ii) the prediction algorithm. This research focuses on aspects of the latter. Using satellite clock data—spanning across several years, corresponding to multiple systems (GPS and GLONASS) and derived from real measurements— this thesis first presents the results of a detailed study into the characteristics of GNSS satellite clocks. This leads onto the development of strategies for modelling and estimating the time-offset of those clocks from system time better, with the final aim of predicting those offsets better. The satellite clock prediction scheme of the International GNSS Service (IGS) is analysed, and the results of this prediction scheme are used to evaluate the performance of new methods developed herein. The research presented in this thesis makes a contribution to knowledge in each of the areas of characterisation, modelling and prediction of GNSS satellite clocks. Regarding characterisation of GNSS satellite clocks, the space-borne clocks of GPS and GLONASS are studied. In terms of frequency stability—and thus predictability—it is generally the case that the GPS clocks out-perform GLONASS clocks at prediction lengths ranging from several minutes up to one day ahead. There are three features in the GPS clocks—linear frequency drift, periodic signals and and complex underlying noise processes—that are not observable in the GLONASS clocks. The standard clock model does not capture these features. This study shows that better prediction accuracy can be obtained by an extension to the standard clock model. The results of the characterisation and modelling study are combined in a Kalman filter framework, set up to output satellite clock predictions at a range of prediction intervals. In this part of the study, only GPS satellite clocks are considered. In most, but not all cases, the developed prediction method out- performs the IGS prediction scheme, by between 10% to 30%. The magnitude of the improvement is mainly dependent upon clock type

Studying resist stochastics with the multivariate poisson propagation model

Progress in the ultimate performance of extreme ultraviolet resist has arguably decelerated in recent years suggesting an approach to stochastic limits both in photon counts and material parameters. Here we report on the performance of a variety of leading extreme ultraviolet resist both with and without chemical amplification. The measured performance is compared to stochastic modeling results using the Multivariate Poisson Propagation Model. The results show that the best materials are indeed nearing modeled performance limits

Inflation dynamics: the role of public debt and policy regimes

Session III-7: Macroeconomics IV - Policy Regimes and DSGE ModelsWe investigate the impact of a time-varying inflation target and changing monetary and fiscal policy stances on the dynamics of inflation in a DSGE model. Under an active monetary and passive fiscal policy regime, inflation closely follows the path of the inflation target and a stronger reaction of monetary policy to inflation decreases the equilibrium response of inflation to non-policy shocks. In sharp contrast, under an active fiscal and passive monetary policy regime, inflation moves in an opposite direction from the inflation target and a stronger reaction of monetary policy to inflation increases the equilibrium response of inflation to non-policy shocks. Moreover, a weaker response of fiscal policy to debt decreases the response of inflation to non-policy shocks. These results are due to variation in the value of public debt that lead to wealth effects on households. Finally, under a passive monetary and passive fiscal policy regime, because of equilibrium indeterminacy, theory provides no clear answer on the behavior of inflation. We characterize these results analytically in a simple model and numerically in a richer quantitative model.postprin

Policy Regimes, Policy Shifts, and U.S. Business Cycles

Session - Monetary EconomicsUsing an estimated DSGE model that features monetary and fiscal policy interactions and allows for equilibrium indeterminacy, we find that a passive monetary and passive fiscal policy regime prevailed in the pre-Volcker period while an active monetary and passive fiscal policy regime prevailed post-Volcker. Since both monetary and fiscal policies were passive pre-Volcker, there was equilibrium indeterminacy that gave rise to self-fulfilling beliefs and resulted in substantially different transmission mechanisms of policy as compared to conventional models: unanticipated increases in interest rates increased inflation and output while unanticipated increases in lump-sum taxes decreased inflation and output. Unanticipated shifts in monetary and fiscal policies however, played no substantial role in explaining the variation of inflation and output at any horizon in either of the time periods. Pre-Volcker, in sharp contrast to post-Volcker, we find that a time-varying inflation target does not explain low-frequency movements in inflation. A combination of shocks account for the dynamics of output, inflation, and government debt, with the relative importance of a particular shock quite different in the two time-periods due to changes in the systematic responses of policy. Finally, in a counterfactual exercise, we show that had the monetary policy regime of the post-Volcker era been in place pre-Volcker, inflation volatility would have been lower by 34% and the rise of inflation in the 1970s would not have occurred.postprin

How entrepreneurial are social entrepreneurship education providers? The role of universities’ entrepreneurial ecosystems in the provision of elective social entrepreneurship courses to business students

With the growing emphasis on social entrepreneurship (SE), many universities are delivering social entrepreneurship courses (SECs) to develop students’ social awareness and aspirations, and socially-entrepreneurial behaviors. This study investigates the extent to which the entrepreneurial ecosystem (EE), entailing entrepreneurism at individual, university and regional levels, may impact on universities’ decisions to offer SECs to business students. Using data from 501 US-based, AACSB-accredited business schools, the finding indicates the importance of the universities’ EE and entrepreneurialism at multi-levels in their commitment to SECs

Optimal Monetary Policy in a Currency Union with Interest Rate Spreads

The Conference papers' website is located at http://dev3.cepr.org/meets/wkcn/1/1806/papers/default.htmPoster Session 1A Euro Area Business Cycle Network (EABCN) ConferenceWe study optimal monetary policy in a two-country currency union model with nominal and financial frictions. In addition to, and independent from, the standard transmission mechanism associated with sticky prices, financial frictions combined with asymmetric asset positions introduce a wealth redistribution role for monetary policy in our model. Financial frictions also lead to a spread between the deposit and borrowing interest rate and variation in the spread affects both aggregate variables, by affecting total spending, and relative (cross-country) variables, by redistributing wealth across countries. Moreover, the interactions between nominal and financial frictions amplify the effects of monetary policy; imply that a strict inflation targeting policy of setting union-wide inflation to zero is never optimal and that optimal policy never attains efficiency; and lead to a novel policy trade-o¤ for the central bank in stabilizing relative consumption versus the relative price gap (the deviation of relative prices from their efficient level). Finally, under optimal monetary policy, in response to an aggregate purely financial shock that causes an increase in the interest rate spread, the central bank strongly decreases the deposit rate, which reduces aggregate and distributional inefficiencies by mitigating the drop in output and inflation and the rise in relative consumption and prices. We also show that while a traditional Taylor rule approximates optimal policy imperfectly, especially in response to the financial shock, a spread-adjusted Taylor rule performs better as it helps the real interest rate track the efficient rate of interest.postprin

Analysis of Customer Satisfaction: Bank of Bhutan Limited

Druk Holding and Investments (DHI) that holds and manages twenty State Owned Enterprises (SOEs) in Bhutan assesses customer satisfaction annually for five service oriented companies through the independent survey to measure customer service related performances of the companies. This paper uses the data collected by the consulting team in 2013 that covers twenty districts of Bhutan. The team collected the data using structured questionnaire covering different aspects of customer satisfaction. Data was collected from 2123 respondents representing various demographic characters. Besides looking into the descriptive aspects of the statistics, this paper analyses the relational between customer satisfaction level and gender, income groups and educational levels so that each group can be targeted with different strategies.  Findings suggest that all types of customers consider service reliability and value for money (price) as the most important factors that attributes to their satisfaction. It was found out that generally females are more satisfied than male respondents at the same level of service quality indicators. Study further establishes the inverse relationships between customer satisfaction level and income and with educational levels of the customers.

Selective Breeding to Improve Productive and Reproductive Performances and Survivability of Indigenous Sakini Chicken

Indigenous chickens are quite popular in Family Poultry Production System (FPPS) in Nepal, but are constrained with their low productive performance. The present study evaluated the productive and reproductive performance of Sakini chicken in different filial generations and sexes. In addition, research also aimed at understanding the effect of generations on above performances. Initially, base populations (G-0) of Sakini were maintained by collecting eight weeks old birds from different agro-ecologial zones of Nepal. Performance of the birds of G-0 was evaluated based on weekly body weight (12-24 weeks), laying performance, fertility, hatchability, hatch weight and survivability. Selected birds of base population (G-0) were used to produce first (G-1), second (G-2) and third (G-3) generations through selective breeding in each generation. Similarly, body weights at hatching, 12 weeks, 16 weeks, 20 week and 24 weeks were significantly (p<0.001) improved from G0 to G3 and were also significantly (p<0.001) differ for sex (males were always heavier than females). Likewise, there was significant (p<0.05) improvement in egg production (per hen per year), age at first lay (days), body weight at sexual maturity, egg number and egg weight at 90 days of laying in progressive generations. Fertility, hatchability and survivability significantly (p<0.05) improved in selected generations in comparison to base population, whereas, no significant difference was obtained within the different selected population. Thus, indigenous Sakini chicken under this experiment performed better with respect to survivability, fertility and hatchability in later generations that provides ample scope of advancing selective breeding activities within the indigenous population in order to bring significant improvement in the overall productive performance of Sakini chicken in Nepal

A shadow function model based on perspective projection and atmospheric effect for satellites in eclipse

Accurate Solar Radiation Pressure (SRP) modelling is critical for correctly describing the dynamics of satellites. A shadow function is a unitless quantity varying between 0 and 1 to scale the solar radiation flux at a satellite’s location during eclipses. Errors in modelling shadow function lead to inaccuracy in SRP that degrades the orbit quality. Shadow function modelling requires solutions to a geometrical problem (Earth’s oblateness) and a physical problem (atmospheric effects). This study presents a new shadow function model (PPM_atm) which uses a perspective projection based approach to solve the geometrical problem rigorously and a linear function to describe the reduction of solar radiation flux due to atmospheric effects. GRACE (Gravity Recovery And Climate Experiment) satellites carry accelerometers that record variations of non-conservative forces, which reveal the variations of shadow function during eclipses. In this study, the PPM_atm is validated using accelerometer observations of the GRACE-A satellite. Test results show that the PPM_atm is closer to the variations in accelerometer observations than the widely used SECM (Spherical Earth Conical Model). Taking the accelerometer observations derived shadow function as the “truth”, the relative error in PPM_atm is −0.79% while the SECM 11.07%. The influence of the PPM_atm is also shown in orbit prediction for Galileo satellites. Compared with the SECM, the PPM_atm can reduce the radial orbit error RMS by 5.6 cm over a 7-day prediction. The impacts of the errors in shadow function modelling on the orbit remain to be systematic and should be mitigated in long-term orbit prediction

Metabolic health and vascular complications in type 1 diabetes

AIMS: Optimal glycaemic control benefits risk of microvascular and macrovascular complications in type 1 diabetes (T1DM) but the importance of other components of metabolic health is less certain, particularly in the context of routine clinical practice. METHODS: Data for this cross-sectional analysis derived from a database covering inner North West London adult diabetes clinics. People with T1DM and with complete information for height, weight, blood pressure and serum high and low-density lipoprotein cholesterol (HDL-c and LDL-c) and triglyceride concentration measurements were included. RESULTS: Among the 920 participants, those with complications were older and had longer duration of diabetes but had similar HbA1c to people without complications. Systolic hypertension and low HDL-c were independently associated with complications. From having 0 risk factors, the prevalence of micro and macrovascular disease increased with increasing number of risk factors. Relative to those with ≥1 risk factor, those with 0 risk factors (n = 179) were at lower risk of retinopathy (OR 0.6 (0.4-0.9), p = 0.01) and nephropathy [OR 0.1 (0.04-0.3), p = 0.002], independent of individual characteristics. CONCLUSIONS: In routine clinical management of T1DM, associations between lipid and blood pressure risk factors and prevalent micro and macrovascular disease remain, implying that more intensive risk factor management may be beneficial