Risk Premium and Central Bank Intervention

This study examines the relation between the risk premium and central bank intervention. Forward rates are calculated for the Turkish Lira-USD exchange market and then the effect of central bank intervention on the risk premium is estimated. Using high quality daily intervention data from the Central Bank of Turkey as well as implied forward rates, an MA (21)-GARCH (1,1) model is estimated. Both purchases and sales of US dollars by the Central Bank of Turkey appear to have no effect on the size of risk premium for TL/USD for the free float period. Similar results are found for the managed float period. Empirical support was weak for the theoretical model, with intervention having a significant effect on the risk premium.Central Bank Intervention, Risk Premium

Analytical prediction of stability limit in turning operations

Unstable cutting due to chatter vibrations is one of the most important problems during metal cutting operations. Chatter can be a limitation for productivity and surface quality in turning operations, especially when long and slender tools and parts are involved. In this study, an analytical stability method for turning process is presented. The model takes the cutting geometry into consideration, and proposes a new solution procedure for the dynamic chip thickness at the insert nose. The analytically calculated absolute stable depth of cuts are compared with the chatter test results, and a good agreement is observed

Experimental analysis and modeling of orthogonal cutting using material and friction models

In this study, a process model for orthogonal cutting processes is proposed. The model involves the primary and secondary deformation zones. The primary shear zone is modeled by a Johnson-Cook constitutive relationship and a shear plane having constant thickness. The secondary deformation zone is modeled semi-analytically, where the coefficient of friction is calibrated experimentally. The cutting forces predicted using the calibrated sliding friction coefficients are in good agreement with the measurements. The experimental investigation of sliding friction coefficients also show promising results for the proposed model, which is still under development

Analytical stability models for turning and boring operations

In this paper an analytical model for stability limit predictions in turning and boring operations is proposed. The multi-dimensional model includes the 3D geometry of the processes. In addition a model for the chip thickness at the insert nose radius is also proposed to observe the effect of the insert nose radius on the chatter stability limit. Chatter experiments are conducted for both turning and boring in order to compare with analytical results and good agreement is observed

Analytical modeling of chatter stability in turning and boring operations: a multi-dimensional approach

In this study, an analytical model for the stability of turning and boring processes is proposed. The proposed model is a step ahead from the previous studies as it includes the dynamics of the system in a multidimensional form, uses the true process geometry and models the insert nose radius in a precise manner. Simulations are conducted in order to compare the results with the traditional oriented transfer function stability model, and to show the effects of the insert nose radius on the stability limit. It is shown that very high errors in stability limit predictions can be caused when the true process geometry is not considered in the calculations. The proposed stability model predictions are compared with experimental results and an acceptable agreement is observed

Long-term Impacts of Annual Cattle Manure and Fertilizer on Soil Quality Under Corn-Soybean Rotation in Eastern South Dakota

Dairy and beef manure have been used to enhance soil quality; however, their impacts under long-term application in corn-soybean rotation need to be evaluated. Nutrient based recommended rates of manure applications on soils are important and also need to be monitored. This study, therefore, was conducted at two long-term sites to assess the impacts of manure and inorganic fertilizer application rates on some of the soil quality indicators and greenhouse gas emissions (GHGs) in a corn (Zea mays L.) - soybean (Glycine max L.) rotation system located at Beresford and Brookings in Eastern South Dakota. Study treatments included: three manure [phosphorus (P) based recommended manure application rate, nitrogen-based recommended manure application rate (N), nitrogen-based double of recommended manure application rate (2N)], and two fertilizers; recommended fertilizer (F) and (HF) high fertilizer and a control (CK) with no manure management. Soil samples were extracted in four replicates under randomized complete block design from 0-10 cm, 10-20 cm, 20-30 cm and 30-40 cm depths to analyze selected soil quality indicators, and intact core samples were taken from 0-10 and 10-20 cm depths to measure soil hydrological properties in 2015. Soil GHG fluxes were observed once a week from June 2015 through October 2015 and May 2016 to August 2016 depending on the climatic conditions. Results showed that manure maintained the soil pH for 0-10 cm depth and inorganic fertilizer decreased it compared to the control treatment at either site. Manure improved soil organic carbon (SOC), total nitrogen (TN), soil aggregate stability (WAS), soil water retention (SWR), water infiltration (qs) but decreased the soil bulk density (BD) in comparison with inorganic fertilizer and control. The CO2 fluxes were significantly impacted by manure application, whereas, there were insignificant impacts on CH4 flux. Soil surface nitrous oxide (N2O) fluxes were significantly impacted by inorganic fertilizer in 2016, whereas, there were nonsignificant differences in 2015. Air temperature and soil moisture content were strongly correlated with soil CO2 fluxes. As a result, this study concluded that manure produced better soil quality by improving soil properties and developing better soil structure, whereas, manure also increased soil surface GHGs emission. The rate of manure application is consequently important for use in agriculture to offer better environmental quality

Modeling dynamics and stability of 5-axis milling processes

5-axis milling is an important machining process for several industries such as aero-space, automotive and die/mold. It is mainly used in machining of sculptured surfaces where surface quality is of extreme importance. Being one of the most important prob-lems in machining, chatter vibrations must be avoided in manufacturing of these com-ponents as they result in high cutting forces, poor surface finish and unacceptable part quality. Chatter free cutting conditions for required quality with higher productivity can be determined by using stability models. Up to now, dynamic milling and stability models have been developed for 3-axis milling operations; however the stability of 5-axis proc-esses has never been modeled. In this paper, a stability model for 5-axis milling opera-tions is proposed. The model can consider the 3D dynamics of the 5-axis milling proc-ess including effects of all important process parameters including lead and tilt angles. Due to the complex geometry and mechanics of the process, the resulting analytical equations are solved numerically in order to generate the stability diagrams

Modeling of temperature distribution in orthogonal cutting with dual-zone contact at rake face

In this study, an analytical model is developed in order to calculate the temperature distribution in orthogonal cutting with dual-zone contact at the rake face. The study focuses on heat generation at the primary shear zone and at the rake face. The material behavior at the primary shear zone is represented by Johnson-Cook constitutive equation whereas the contact at the rake face is modeled by sticking and sliding friction zones. This new temperature distribution model allows obtaining the maximum temperature at the rake face and helps determining two dimensional temperature distribution in the chip. The simulation results obtained from the developed model are also compared with experimental results where good agreement is observed

Joint decisions on inventory replenishment and emission reduction investment under different emission regulations

Cataloged from PDF version of article.Carbon emission regulation policies have emerged as mechanisms to control firms’ carbon emissions. To meet regulatory requirements, firms can make changes in their production planning decisions or invest in green technologies. In this study, we analyse a retailer’s joint decisions on inventory replenishment and carbon emission reduction investment under three carbon emission regulation policies. Particularly, we extend the economic order quantity model to consider carbon emissions reduction investment availability under carbon cap, tax and cap-and-trade policies. We analytically show that carbon emission reduction investment opportunities, additional to reducing emissions as per regulations, further reduce carbon emissions while reducing costs. We also provide an analytical comparison between various investment opportunities and compare different carbon emission regulation policies in terms of costs and emissions. We document the results of a numerical study to further illustrate the effects of investment availability and regulation parameters