Academic literature on the topic 'Difficult unsymmetry'

The multivariable PID neural network (MPIDNN) control system is introduced in this paper. MPIDNN is used to perform both the control and the decouple at the same time and to get better performance. It is difficult to control multivariable system by conventional controller because the strong coupling properties of the system. Generally, the decoupling system should be designed first and the multivariable object would be divided into several single variable objects. Then, several simple controller would achieve the control of those objects. The decoupling system and the controller exist in theory but the design process is very difficult actually because the transfer function of the object is difficult to get. Especially, if the number of the object inputs is not equal to that of the object outputs, which is called unsymmetry object, the conventional decoupling is impossible. A actual example is discussed in the paper in order to prove the function of the MPIDNN, in which an un-symmetry multivariable system which has 3 inputs and 2 outputs is controlled by a MPIDNN and the perfect control property is obtained by self-learning process.

Self-organizing map (SOM) has been used in protein folding prediction when the HP model is employed. The existing work uses a square-like shape lattice with l = m×n points to represent the optimal compact structure of a sequence of l amino acids. In this paper, a general l′-size sequence of amino acids is self-organized in a two dimensional lattice with l (> l′) points. The obtained minimum configuration then has a flexible shape, in contrast to the compact structure limited in the lattice. To fulfil this extension, a new self-organizing map (SOM) technique is proposed to deal with the difficulty of the unsymmetric input and output spaces. New competition rules in the training phase are introduced and a local search method is applied to overcome the multi-mapping phenomena. Several HP benchmark examples with up to 36 amino acids are tested to verify the effectiveness of the proposed approach in this paper.

The use of threaded connection is a valuable alternative to conventional welding in tubularconstructions, e.g. pipelines, drill pipes and deep water risers. Those applications are normally exposed toenvironmental hazards – wave induced vibrations, temperature changes, etc. – as well as subjected tosevere service conditions. A classical way to determine fatigue strength in many engineering situations is tocalibrate material models by means of ad hoc designed experiments. Unfortunately, it is very difficult in thiscase even under laboratory conditions due to complicated stress and strain states in the contacting taperedhelical thread surfaces of the connection. Therefore, a classical four-point bending fatigue test setup hasbeen built with a real pipe specimen of 3.75 meter long, consisting of two standard API pipes connected bya threaded coupling, under unsymmetric (non-zero average) load control cycles. A complete vibration studyhas been carried out based on input-output modal tests for the entire period of the fatigue experiment. Inputexcitation is due to hammer impact and responses are recorded by accelerometers and by reusabledynamic strain gauges. The measured modal strains from the dynamic strain gauges allow for directcalculation of the modal curvatures, rather than deriving approximately from acceleration information. Bycomparing the measured modal parameters with those of a numerical model of the same structure inundamaged condition, damage detection, localization in the coupling and quantification are possible. Thisstudy leads to the following conclusion of practical use: the recent advancement in modal analysis, i.e. thereference based input-output combined deterministic-stochastic subspace identification, makes it possibleto identify the structural modal properties from in-situ modal tests, which are performed while the fatiguetest is ongoing. In this way the fatigue test is uninterrupted to avoid the problem of stress and straindisturbances happened in un-reversing load cycles test.

AbstractDirectly accessible 8-substituted tetrahydroquinolines undergo 1,5-hydride-shift-triggered cyclization to provide difficult to access julolidine derivatives in yields of 21–98% under scandium(III) triflate catalysis. Additionally, the scope of the reaction, several follow-up transformations and a remarkable side process discovered during optimization of the conditions are highlighted.

Дисертація на здобуття наукового ступеня доктора технічних наук за спеціальністю 05.14.02 – Електричні станції, мережі та системи. – ДВНЗ «Донецький національний технічний університет», Донецьк, 2010. Дисертація присвячена вирішенню важливої науково-технічної проблеми – розробці теоретичних основ, методів і засобів математичного моделювання електричних систем з простою і складною несиметрією в стаціонарних і перехідних режимах, що орієнтовані на сучасний рівень розвитку засобів обчислювальної техніки і забезпечують підвищення ефективності процесів як моделювання, так і розробки моделей таких систем. У роботі сформульовано і реалізовано узагальнений, системний підхід до завдань математичного моделювання стаціонарних і перехідних режимів електричних систем з несиметрією на основі узагальнених, багатофункціональних математичних моделей і макромоделювання у фазних координатах, розроблені і практично реалізовані методи, моделі і засоби, що дозволяють ставити і вирішувати широке коло завдань, які в рамках моделей, традиційно орієнтованих на спрощення завдання шляхом заміни реальних трифазних систем однофазними еквівалентами, не вирішуються або вирішуються лише приблизно. Розроблено базові математичні моделі, що дозволяють досліджувати стаціонарні режими, електромагнітні та електромеханічні перехідні процеси електричних систем довільного складу і структури з несиметрією будь-якого вигляду з урахуванням всіх основних впливаючих чинників. Основні наукові і практичні результати роботи широко упроваджені у виробництво.
Dissertation for getting of the scientific degree of doctor of technical sciences on speciality 05.14.02 “Electrical stations, nets and systems. Donetck National Technical Universiti, Donetsk, 2010. Dissertation is devoted the decision of important scientific and technical problem – development of theoretical bases, methods and facilities of mathematical design of the electric systems with stand and by difficult unsymmetry in the stationary and transitional modes, oriented to the modern level of development of facilities of the computing engineering and providing the increase of efficiency of processes of both design and development of models of such systems. In-process formulated and realized the generalized, system going near the tasks of mathematical design of the stationary and transitional modes of the electric systems with unsymmetry on the basis of the generalized, multifunction mathematical models and macromodeling in phase coordinates, developed and methods, models and facilities, allowing to put and decide the wide circle of tasks, which within the framework of models, traditionally orientable on simplification of task substitutionally by monophase equivalents the real three-phase systems, do not decide or decide only approximately, are practically realized. Base mathematical models, allowing to probe the stationary modes, are developed, electromagnetic and electromechanics transients of the electric systems of arbitrary composition and structure with unsymmetry of any kind taking into account all of basic influences. Basic scientific and practical job performances are widely applied in industry.