Insights from unifying modern approximations to infections on networks

Networks are increasingly central to modern science owing to their ability to conceptualize multiple interacting components of a complex system. As a specific example of this, understanding the implications of contact network structure for the transmission of infectious diseases remains a key issue in epidemiology. Three broad approaches to this problem exist: explicit simulation; derivation of exact results for special networks; and dynamical approximations. This paper focuses on the last of these approaches, and makes two main contributions. Firstly, formal mathematical links are demonstrated between several prima facie unrelated dynamical approximations. And secondly, these links are used to derive two novel dynamical models for network epidemiology, which are compared against explicit stochastic simulation. The success of these new models provides improved understanding about the interaction of network structure and transmission dynamics

Effect of Rake Angle on Stress, Strain and Temperature on the Edge of Carbide Cutting Tool in Orthogonal Cutting Using FEM Simulation

Demand for higher productivity and good quality for machining parts has encourage many researchers to study the effects of machining parameters using FEM simulation using either two or three dimensions version. These are due to advantages such as software package and computational times are required. Experimental work is very costly, time consuming and labor intensive. The present work aims to simulate a three-dimensional orthogonal cutting operations using FEM software (deform-3D) to study the effects of rake angle on the cutting force, effective stress, strain and temperature on the edge of carbide cutting tool. There were seven runs of simulations. All simulations were performed for various rake angles of -15 deg, -10 deg, -5 deg, 0 deg, +5 deg, +10 deg, and +15 deg. The cutting speed, feed rate and depth of cut (DOC) were kept constant at 100 m/min, 0.35 mm/rev and 0.3 mm respectively. The work piece used was ductile cast iron FCD500 grade and the cutting tool was DNMA432 series (tungsten, uncoated carbide tool, SCEA = 0; and radius angle 55 deg). The analysis of results show that, the increase in the rake angle from negative to positive angle, causing the decrease in cutting force, effective stress and total Von Misses strain. The minimum of the cutting force, effective stress and total Von Misses strain were obtained at rake angle of +15 deg. Increasing the rake caused higher temperature generated on the edge of carbide cutting tool and resulted in bigger contact area between the clearance face and the workpiece, consequently caused more friction and wear. The biggest deformation was occurred in the primary deformation zone, followed by the secondary deformation zone. The highest stress was also occurred in the primary deformation zone. But the highest temperature on the chip usually occurs in secondary deformation zone, especially in the sliding region, because the heat that was generated in the sticking region increased as the workpiece was adhered by the tool and later it was sheared in high frictional force

Disclosure Of EVA Use In Corporate Financial Reports: A Descriptive Analysis

This descriptive study examines a sample of 269 firms that mentioned EVA in their public disclosures.  The key findings of our study are: (1) the use of EVA is found in a cross-section of the industries; (2) the most commonly used source of disclosure is the proxy statement; (3) a majority of the firms use only EVA rather than EVA in combination with other traditional measures; (4) a majority of the sample firms apply EVA at the corporate level alone; (5) three-fourths of the sample firms use EVA as an incentive compensation tool; (6) most firms apply EVA and other metrics only at the executive level for compensation and performance evaluation; and (7) two common modes of compensation using EVA determination are bonus plans and stock options.  The results of our study indicate that firms are steadily adopting EVA as one component of their value management system.  In a related decision context, investors estimate the cost of equity capital to arrive at the intrinsic value of the firm.  Firms can help investors reduce this estimation error by reporting their own estimate of the cost of equity capital, in turn, reducing the valuation error. Our findings have implications for the Securities and Exchange Commission and the Financial Accounting Standards Board in that they should recognize the need to address this issue thereby enhancing the decision usefulness of public reporting

Parameters Affecting the Extraction Process of Jatropha Curcas Oil Using a Single Screw Extruder

The most commonly used technique to separate oil and cake from J. curcas seeds is mechanical extraction. It uses simple tools such as a piston and a screw extruder to produce high pressure, driven by hand or by engine. A single screw extruder has one screw rotating inside the barrel and materials simultaneously flow from the feed to the die zone. The highest oil yield can be obtained by a well-designed oil press as well as finding the optimum conditions for all parameters involved during the extraction process. The influence of the parameters in a single screw extruder was studied using finite element analysis and computational fluid dynamics simulation with ANSYS POLYFLOW. The research focused on predicting the velocity, pressure and shear rate in the metering section that influenced the screw rotational speed and mass flow rate. The obtained results revealed that increasing the screw rotational speed will increase the pressure, velocity and shear rate. Meanwhile, increasing the mass flow rate results in decreasing the pressure while the velocity and shear rate remain constant

The Novel Digital Image Correlation Technique in Predicting Behaviour and Failure of Hybrid Composite

This paper presents a technique in measuring deformation occurs on in-plane hybrid composite CFRP/GFRP. The challenging task of extracting mechanical properties of the hybrid composite is assisted with the use of Digital Image Correlation (DIC) technique. DIC is an innovative technique which able to capture full field deformation of tensile deformation. The complex deformation captured for hybrid composite in-plane tensile deformation and behavior using Digital Image Correlation (DIC) under static loading is a new area of study in literature. Generally, hybrid composite consists of more than one reinforcing sections or multiple reinforcing or multiple matrix sections or single reinforcing phase with multiple matrix phases. As a result of a compromise between the materials within the hybrid composite, the deformation and stress analysis are to be evaluated and tailored as each constituent of material carry their own desired mechanical properties according to a performance requirement. It is found in relation of stress-strain relationship of hybrid composite under tensile loading via DIC, the modulus of elasticity is found to record value around 92-97GPa which in theoretical benchmark located in between value of Modulus of Elasticity, E1 for CFRP(120GPa) and GFRP(42GPa) which proves the occurrence of the hybrid effect. It is a new research area in utilizing digital image correlation (DIC) technique on hybrid composite rather than conventional composite in material characterization

Comparison of large aperture scintillometer and eddy covariance measurements: Can thermal infrared data be used to capture footprint-induced differences?

Eddy covariance (EC) and large aperture scintillometer (LAS) measurements were collected over an irrigated olive orchard near Marrakech, Morocco. The tall, sparse vegetation in the experimental site was relatively homogeneous, but during irrigation events spatial variability in soil humidity was large. This heterogeneity caused large differences between the source area characteristics of the EC system and the LAS, resulting in a large scatter when comparing sensible heat fluxes obtained from LAS and EC. Radiative surface temperatures were retrieved from thermal infrared satellite images from the Landsat Enhanced Thematical Mapper and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellites. Using these images in combination with an analytical footprint model, footprint-weighted radiative surface temperatures for the footprints of the LAS and the EC system were calculated. Comparisons between the difference in measured sensible heat fluxes and the difference in footprint-weighted radiative surface temperature showed that for differences between the footprint-weighted radiative surface temperatures larger than 0.5 K, correlations with the difference in measured sensible heat flux were good. It was found that radiative surface temperatures, obtained from thermal infrared satellite imagery, can provide a good indication of the spatial variability of soil humidity, and can be used to identify differences between LAS and EC measurements of sensible heat fluxes resulting from this variability

Calibration and validation of the STICS crop model for managing wheat irrigation in the semi-arid Marrakech/Al Haouz Plain

In the first part of this work, the shoot growth module and grain yield of the STICS crop model were calibrated and validated by using field data which was collected from irrigated winter wheat fields in the Haouz plain near Marrakech. The calibration was performed on the thermal units between the four phenological stages that control the dynamics of leaf area index and the thermal unit between emergence and the beginning of grain filling. The plant phenology was calibrated for three fields monitored during the 2002/03 season. Evaluation of the grain yields and the temporal evolution of leaf area index were done for six validation fields during 2003/04. The results showed the significant accuracy of the model in simulating these variables, and also indicated that the plants mainly suffered from lack of nitrogen. The results in the second part show the potential of crop modeling to schedule irrigation water, on the assumption that the plants were growing under optimal conditions of fertilization. In this case, the model was used to manage the time of irrigation according to a threshold for water deficit. Various simulations displayed logical trends in the relationship between the grain yield and both the amount and timing of irrigation water. These results were finally compared with those obtained from real irrigation practices. For the particular climate of 2003/04, the comparison showed that 70 mm and 40 mm of water could be saved in case of early and late sowing, respectively