Abstract Most of the controllers used in industries are of PID type, this is because they have simple structure and their usage is well known among industrial specialists. The tuning of controllers is the crucial issue in the overall control loop design in order to obtain a satisfactory performance response. Over the past decades many tuning techniques were developed to adjust the controller parameters. Most of these techniques have the disadvantages of giving a combination of heavy oscillatory response, large overshoot, and long settling and rise time. This work presents a fuzzy logic-PID scheme, the basic concept behind this scheme is to combine the conventional PID controller with the use of fuzzy logic concept. The PID controller regulates the process, while the fuzzy logic part adjusts the proportional gain of the controller. This scheme will be used to overcome the previous disadvantages and to improve the performance of the conventional controller. The effectiveness of fuzzy logic-PID scheme has been analyzed through computer simulation using MATLAB. The results have been compared with those of Ziegler-Nichols, Chien-Hrones-Reswick, Cohen-Coon, Optimum PID controller and a PID with constant and variable weighting factor. This comparison has shown a considerable improvement in the performance of the transient response for different simulated processes
علي عبدالرحمن بن عاشور (2008)

التصوير الطبقي ذو المعاوقة الكهربائية (EIT) هو تقنية تسمح بإعادة بناء صور المقطع العرضي المتعلقة بالمعاوقة الكهربائية من خلال مجموعات مقاسه من سطحها، الدافع الرئيسي من تطوير التصوير الطبقي ذي المعاوقة الكهربائية(EIT)هواحتمالية تطبيقه في مجالات التصوير الطبية، وكما هو معروف فأن النسيج الحيوي له مدي معاوقة كهربائية واسع والعديد من الأحداث الفسيولوجية محسوبة بتغيرات المعاوقة الكهربائية، و موصلية نسيج جسم الإنسان فيها اختلافات كبيرة، لذا يجب أن تعطي صور الموصلية مقارنة عالية بين الأنسجة الناعمة. وتعتمد تقنية التصوير الطبقي ذي المعاوقة الكهربائية على إعادة بناء توزيع الموصلية في جسم الإنسان، وذلك من خلال القياسات الخارجية التي يتم قياسها عند تمرير التيار خلال المجسات الموجودة على الجسم والتيار المار، والجهد المقاس يعتمد على الموصلية المراد إيجادها، وتهدف كل خوارزمياتِ وإعادةَ البناء إلي تَقليل الأخطاءِ، والحصول على صور ممتازةِ. إعادة بناء الموصلية في التصوير الطبقي ذي المعاوقة الكهربائية (EIT) تعتبر مشكلة، وبشكل عملي تحل هده المشكلة ببعض طرق التنظيم أو الفرضيات المطبقة لتحسين نوعية الصورة.للحصول على أفضل بناء صورة ممكنه للتصوير الطبقي ذي المعاوقة الكهربائية تم في هذا العمل إجراء مقارنة بين العديد من طرق التنظيم وكانت معتمدة على تعديل النسبة بين أكبر وأصغر القيم الصغيرة والقريبة للصفر داخل مصفوفة الحساسية وتم تطبيق ذلك في طريقة جديدة.كما تم في هذا العمل أيضاً تطوير طريقة جديدة تتعلق بالتصوير الطبقي ذي المعاوقة الكهربائية وتسجيل الصورة و تم الحصول على المعلومات الكاملة في الصورة الجديدة. Abstract Electrical Impedance Tomography (EIT) is a technique which allowscross-section images related to the local electrical impedance within an object to be reconstructed from sets of measurements made on its surface. The main drive behind the development of Electrical Impedance Tomography (EIT) has been its possible application in medical imaging, as biological tissues are known to exhibit a wide range of electrical impedances and many physiological events are computed by electrical impedance changes. The conductivity of the human tissue has large variations so images of the conductivity distribution should give high contrast of soft tissues. In electrical impedance tomography (EIT) the conductivity distribution is reconstructed from measured boundary potential when current sources are applied to the boundary of the object. Both internal current paths and potential distribution depend on the unknown conductivity distribution. All considerations of the reconstruction algorithms aim to minimize the errors, and to obtain quality images.Reconstruction of the conductivity distribution in electrical impedance tomography (EIT) is an un-determined and ill-posed problem. Typically requiring simplifying assumption or regularization methods to improve image quality.To improve the system’s conditioning and to determine the best image reconstruction in electrical impedance tomography (EIT) several regularization methods in this work are compared, and based on modification of the ratio between the largest and the smallest non-zero singular value of the sensitivity matrix, a new method has been developed.Also in this work a new method concerning electrical impedance tomography image registration has been developed and the full information contained in the new image can be obtained.
زينب احمد العزابى (2008)

Abstract In practical environment most of physical systems that are existed, have nonlinear behavior. In most cases the accuracy of these systems, and their responses aren’t acceptable. Therefore to improve the performance of these systems, a modern control methodology must be applied. In the case of nonlinear systems most problems can be divided into two basic types of nonlinear control problems; nonlinear regulation and nonlinear tracking problems. Due to existing of high nonlinearities parts in theses nonlinear systems the use of classical linearization methods don’t provide an acceptable level of accuracy and therefore these problems have gained a great attention in recent years; and there are numbers of methods can be found to solve these nonlinear problems, such as trail and error, feedback linearization, Robust control, Adaptive control, Gain-scheduling and…etc. In This thesis the feedback linearization is choose as a control methodology to solve these problems; The central idea of the feedback linearization approach is to algebraically transform a nonlinear system dynamics into a (fully or partly) linear one, so that linear control techniques can be applied. This differs entirely from conventional linearization (i.e., Jacobian linearization [4]) in that feedback linearization is achieved by exact state transformations and feedback, rather than by linear approximations of the dynamics.
فرج على عبدالسلام بشير (2008)