Hiding biometric data

With the wide spread utilization of biometric identification systems, establishing the authenticity of biometric data itself has emerged as an important research issue. The fact that biometric data is not replaceable and is not secret, combined with the existence of several types of attacks that are possible in a biometric system, make the issue of security/integrity of biometric data extremely critical. We introduce two applications of an amplitude modulation-based watermarking method, in which we hide a user's biometric data in a variety of images. This method has the ability to increase the security of both the hidden biometric data (e.g., eigen-face coefficients) and host images (e.g., fingerprints). Image adaptive data embedding methods used in our scheme lead to low visibility of the embedded signal. Feature analysis of host images guarantees high verification accuracy on watermarked (e.g., fingerprint) images.     

Use of levodopa to relieve pain from painful symmetrical diabetic polyneuropathy

Levodopa has been used to treat some painful conditions and found to be effective in neuropathic pain due to herpes zoster in a double-blind study. From our anecdotal observations about the efficacy of levodopa on diabetic neuropathic pain, we designed a double-blind placebo-controlled study to test levodopa in painful diabetic neuropathy. Twenty-five out-patients with painful symmetrical diabetic polyneuropathy were admitted to the study. Fourteen patients were given 100 mg levodopa plus 25 mg benserazide to be taken three times per day for 28 days. Eleven patients were given identical placebo capsules. A blinded neurologist evaluated the patients clinically and performed Visual Analogue Scale (VAS) measurement every week from day 0 to day 28. The results seemed promising and levodopa may be a choice for the control of pain in neuropathy for which we do not have many alternative treatments.     

Biometric cryptosystems: issues and challenges

In traditional cryptosystems, user authentication is based on possession of secret keys; the method falls apart if the keys are not kept secret (i.e., shared with non-legitimate users). Further, keys can be forgotten, lost, or stolen and, thus, cannot provide non-repudiation. Current authentication systems based on physiological and behavioral characteristics of persons (known as biometrics), such as fingerprints, inherently provide solutions to many of these problems and may replace the authentication component of traditional cryptosystems. We present various methods that monolithically bind a cryptographic key with the biometric template of a user stored in the database in such a way that the key cannot be revealed without a successful biometric authentication. We assess the performance of one of these biometric key binding/generation algorithms using the fingerprint biometric. We illustrate the challenges involved in biometric key generation primarily due to drastic acquisition variations in the representation of a biometric identifier and the imperfect nature of biometric feature extraction and matching algorithms. We elaborate on the suitability of these algorithms for digital rights management systems.     

Effect of heat treatment on the creep behavior of α/β SiAlON sintered with multication oxide sintering additives

SiAlONs are important materials for high-temperature applications and creep properties of SiAlONs are largely controlled by the amount and type of sintering additives. It has been established that heat treatment can reduce the amount of amorphous intergranular phase through crystallization. However, there is no study on the creep behavior of heat-treated SiAlON ceramics containing multication sintering additives. Therefore, the aim of the study was to investigate the effect of heat treatment on the creep properties of multication containing (Y-Sm-Ca oxides) α/β-SiAlON ceramics. The heat treatments of the sintered samples were carried out at 1600°C for 2 hours. The creep tests were carried out in the range 1300-1400°C under different loads (50-150 MPa). The existing phases and the microstructures of samples before and after creep were investigated using XRD and SEM techniques. It was found that heat treatment resulted in a better creep performance compared to as-sintered samples. The activation energy and stress exponent for heat-treated SiAlONs were also calculated as 708 ± 45 kJ/mol and 1.4, respectively. Compared to the sintered sample values, the results suggested that the acting creep mechanism of grain-boundary sliding and cavitation was reduced with the heat treatment.     

Dynamic wind turbine output power reduction under varying wind speed conditions due to inertia

The inertia of wind turbines causes a reduction in their output power due to their inability to operate at the turbine maximum co‐efficient of performance point under dynamic wind conditions. In this paper, this dynamic power reduction is studied analytically and using simulations, assuming that a steady‐state optimal torque control strategy is used. The concepts of the natural and actual turbine time‐constant are introduced, and typical values for these parameters are examined. It is shown that for the typical turbine co‐efficient of performance curve used, the average turbine speed can be assumed to be determined by the average wind speed. With this assumption, analytical expressions for the power reduction with infinite and then finite turbine inertia are determined for sine‐wave wind speed variations. The results are then generalized for arbitrary wind speed profiles. A numerical wind turbine system simulation model is used to validate the analytical results for step and sine‐wave wind speed variations. Finally, it is used with real wind speed data to compare with the analytical predictions. Copyright © 2012 John Wiley & Sons, Ltd.