The environmental Kuznets curve for US counties: A spatial econometric analysis with extensions

We examine the relationship between county per capita income and toxic pollutants using a comprehensive model of the Environmental Kuznets Curve. The model incorporates ethnic diversity, spatial effects and most independent variables used in previous studies. Initial results suggest that the relationship follows an inverted-U-shape. However, incorporation of a cubic term for income reveals that toxic pollution eventually increases again as income continues to rise. Ethnic diversity and spatial effects are found to be important in understanding toxic pollution in US counties. We also detect an EKC-type relationship with respect to income inequality.Received: 25 January 2002, Accepted: 8 March 2003, JEL Classification: R11, Q20The authors gratefully acknowledge funding from the US Department of Agriculture under NRI Grant No. 00-5401-9320, as well as the comments of three anonymous reviewers. An earlier version of this article was presented at the North American Regional Science Association meetings in Charleston, SC in November 2001.     

Electromigration reliability evaluation for a three-level metallization process

The electromigration behaviour of triple level Al-1%Si-0.5%Cu thin films is presented as used in a metallization process necessary for high-density CMOS (HDCMOS) ASIC technology. A prediction time-to-failure (TTF_x) formula has been fit and the 0.01% cumulative-failure-function F(t) vs. time has been calculated. Reliability improvement was achieved by using test vehicles baked for t=1400 hrs at T=200°C.Maximum current density design rules are derived as a function of the sigma value for each metal level.     

Estimation and projections of demand for crude petroleum and refined petroleum products

The purpose of this article is to estimate the demand and supply relationships of the US petroleum market. By measuring the elasticities and cross-elasticities of demand, the relative responsiveness of changes in prices and income and the possibility of substitution of alternative energy resources for petroleum are determined. The demand for refined products is also estimated. Finally, through projection of the demand for, and the domestic supply and imports of crude petroleum under alternative assumptions, a measure of the magnitude of physical reserves and capital requirements is obtained for policies of self-sufficiency and free trade.     

Execution transactions for defending against software failures: use and evaluation

We examine the problem of containing buffer overflow attacks in a safe and efficient manner. Briefly, we automatically augment source code to dynamically catch stack and heap-based buffer overflow and underflow attacks, and recover from them by allowing the program to continue execution. Our hypothesis is that we can treat each code function as a transaction that can be aborted when an attack is detected, without affecting the application's ability to correctly execute. Our approach allows us to enable selectively or disable components of this defensive mechanism in response to external events, allowing for a direct tradeoff between security and performance. We combine our defensive mechanism with a honeypot-like configuration to detect previously unknown attacks, automatically adapt an application's defensive posture at a negligible performance cost, and help determine worm signatures. Our scheme provides low impact on application performance, the ability to respond to attacks without human intervention, the capacity to handle previously unknown vulnerabilities, and the preservation of service availability. We implement a stand-alone tool, DYBOC, which we use to instrument a number of vulnerable applications. Our performance benchmarks indicate a slow-down of 20% for Apache in full-protection mode, and 1.2% with selective protection. We provide preliminary evidence toward the validity of our transactional hypothesis via two experiments: first, by applying our scheme to 17 vulnerable applications, successfully fixing 14 of them; second, by examining the behavior of Apache when each of 154 potentially vulnerable routines are made to fail, resulting in correct behavior in 139 cases (90%), with similar results for sshd (89%) and Bind (88%).     

A PKI approach for deploying modern secure distributed e-learning and m-learning environments

While public key cryptography is continuously evolving and its installed base is growing significantly, recent research works examine its potential use in e-learning or m-learning environments. Public key infrastructure (PKI) and attribute certificates (ACs) can provide the appropriate framework to effectively support authentication and authorization services, offering mutual trust to both learners and service providers. Considering PKI requirements for online distance learning networks, this paper discusses the potential application of ACs in a proposed trust model. Typical e-learning trust interactions between e-learners and providers are presented, demonstrating that robust security mechanisms and effective trust control can be obtained and implemented. The application of ACs to support m-learning is also presented and evaluated through an experimental test-bed setup, using the general packet radio service network. The results showed that AC issuing is attainable in service times while simultaneously can deliver flexible and scalable solutions to both learners and e-learning providers.     

Aerodynamic performance of a dual turbine concept characterized by a relatively close distance between rotors

In this work, a closely spaced dual turbine concept is studied. The distance between the two side-by-side hubs is 1.05 $D$, where $D$ is the rotor diameter. This configuration has a potential benefit for offshore wind developments in which power density can be maximized. The main goal is to evaluate the overall aerodynamic performance, blade loads, and wake structure of a reference wind turbine generator operating within this dual turbine configuration and to compare the effects against those for the typical single turbine configuration. For this purpose, an actuator line model has been employed together with the large eddy simulation approach for predicting the turbulence effects. This model was implemented by using the open-source computational fluid dynamics toolbox OpenFOAM. Results show a better performance for the dual turbine concept. Under same operating conditions, the aerodynamic power of each turbine within the dual concept is higher than the power of the stand alone turbine, particularly at lower operating wind speeds (approximately 2% to 3% of extra power per turbine). Comparison between the two configurations shows similar character of the tangential and normal forces acting on the blades in terms of magnitude and fluctuation, eliminating potential concerns regarding fatigue and blade design. The largest difference in the tangential and normal root bending moments are approximately 3% and 2%, respectively, between single and dual turbine configurations. Finally, wake recovery analysis shows a downwind velocity deficit that is not enhanced streamwise in the dual turbine configuration with no considerable difference after 7 $D$.     

Hierarchical clustering of mixed-type data based on barycentric coding

Behaviormetrika - Clustering of mixed-type datasets can be a particularly challenging task as it requires taking into account the associations between variables with different level of measurement,...     

Towards a wicking rapid test for rejection assessment of reused fried oils: Results and analysis for extra virgin olive oil

This work investigates the potential of developing a rapid test based on wicking of oil into paper for determining whether a reused frying oil is to be rejected. To achieve this goal, wicking patterns (oil penetration rate and oil front shape versus time) of both fresh and prolonged fried extra virgin olive oil are optically registered at six different paper stripes. Four of them are double-ply towel papers whereas the other two are single-ply chromatographic papers. Wicking tests are performed at 20 °C and 30 °C. It is shown that the type of paper affects seriously the wicking patterns. Double-ply papers present high oil penetration rates but very irregular oil front shapes whereas single-ply papers yield lower oil penetration rates but pretty flat oil fronts. Furthermore, it is found that only under certain conditions the penetration rates obey the well known Lucas–Washburn equation. A discussion is made on the phenomena that take place during wicking of oil into paper which may cause deviations from the Lucas–Washburn equation. A semi-empirical model is proposed to describe the above deviations by incorporating the effect of time evolving pore sizes.