Integration of safety risk assessment techniques into requirement elicitation

Incomplete and incorrect requirements may cause the safety-related software systems to fail to achieve their safety goals. It is crucial to ensure software safety by identifying proper software safety requirements during the requirements elicitation activity. Practitioners apply various Safety Risk Assessment Techniques (SRATs) to identify, analyze and assess safety risk.Nevertheless, there is a lack of guidance on how appropriate SRATs and safety process can be integrated into requirements elicitation activity to bridge the gap between the safety and requirements engineering practices. In this research, we proposed an Integration Framework that integrates safety activities and techniques into existing requirements elicitation activity

Processing the Couette viscometry data of molasses by Tikhonov regularisation

This paper highlights a general and reliable technique for converting basic torque-rotational speed for molasses derived from Couette viscometers into true shear stress-shear rate data without a priori assumption of a fluid model. Obtaining the shear rate as a function of shear stress from Couette viscometry data is an inverse problem and is normally 'solved' by assuming a rheological model such as a power law model. An accurate method based on Tikhonov regularisation is developed to solve this inverse problem for the shear rate. The advantages of Tikhonov regularisation are highlighted. The performance of the new method is assessed by applying it to process the Couette data of molasses

Obtaining the shear stress-shear rate function and the wall shear stress-slip velocity function of PVC melts from slit-die viscometry data

Shear stress versus shear rate and wall shear stress versus slip velocity relations are the key material property functions of any polymer melts. They are normally measured using capillary or slit viscometers. The presence of wall slip greatly complicates the treatment of the resulting viscometry data. This paper describes the conversion of the viscometry data of a number of PVC melts through slit dies with different gaps into these two material property functions. The conversion procedure, based on Tikhonov\ud regularization, has the advantage that it is independent of rheological constitutive equation and does not require extrapolation of the experimental data. It also has the ability to cope with the unavoidable noise in the experimental data. Consequently, the resulting property functions are likely to be closer to the true material properties than some of the existing methods. For each PVC melt investigated the two material property functions will be compared against published results and their differences discussed

Obtaining the shear stress shear rate relationship and yield stress of liquid foods from Couette viscometry data

A method based on Tikhonov regularisation is used to convert the Couette viscometry data of a number of liquid foods into shear stress vs shear rate relationships. For liquid foods that have a yield stress and if the viscometry data cover the appropriate range of shear stress, Tikhonov regularisation is used to compute simultaneously the yield stress. The versatility of Tikhonov regularisation is demonstrated by applying it to process data from wide as well as narrow gap Couette viscometers. The results generated by Tikhonov regularisation are compared against that obtained by methods currently employed by rheologists

Applying Tikhonov regularization to the time-concentration data of reaction kinetics

[Extract] Experimental data of reaction kinetics are usually in the form of concentration or mole fraction versus time. For kinetic investigation, such as determination of the appropriate\ud reaction rate expression, it is more convenient to have the data in the form of reaction rate versus concentration. Converting time-concentration data into concentration reaction rate data by direct numerical differentiation of experimental kinetic data will amplify the noise in the data leading to unreliable results [I]. This paper describes a conversion procedure in which the differentiation process is replaced by one of solving an integral equation of the first\ud kind. The integral equation is then solved by Tikhonov regularization a well-proven method for handling this class of equations [I]. This procedure leads to a smooth concentration reaction rate curve that is independent of kinetic model and manages to keep noise amplification under control.\ud \ud The performance of this procedure is demonstrated by applying it to kinetic data taken from the published literature. Since these data are accompanied by their rate expressions, the\ud computed rates are used to obtain the unknown parameters in these expressions. Comparison of the results with published figures and the ease with which they are obtained highlight the\ud advantages of the new procedure. Where necessary the rate expression is modified and new/additional parameters are obtained. This fin al step shows the flexib ility of Tikhonov\ud regularization as a general tool for investigating alternative kinetic models

Impact of Postgrafting Immunosuppressive Regimens on Nonrelapse Mortality and Survival after Nonmyeloablative Allogeneic Hematopoietic Stem Cell Transplant Using the Fludarabine and Low-Dose Total-Body Irradiation 200-cGy

10.1016/j.bbmt.2007.03.002Biology of Blood and Marrow Transplantation137790-80