A study of structure of meta and para substituted phenyl and benzoyl isothiocyanates by the MNDO method

1987 ◽  
Vol 52 (9) ◽  
pp. 2115-2124 ◽  
Author(s):  
Ivan Danihel ◽  
Pavol Kristian ◽  
Stanislav Böhm ◽  
Josef Kuthan
Keyword(s):  
Electron Distribution ◽  
Dipole Moments ◽  
Point Of View ◽  
Mndo Method ◽  
Mndo Calculations ◽  
Non Linear ◽  
Benzoyl Isothiocyanates

On the basis of the optimized MNDO calculations of a selected series of meta and para substituted phenyl and benzoyl isothiocyanates it has been found that the –NCS group is non-linear in both the cases (the deviation from linearity is about 9°). For the phenyl isothiocyanates the values of CNC angles are in the region of 146.1° - 149.0°, and for the benzoyl isothiocyanates the respective regions for the CNC and OCN angles are 146.4° - 152.1° and 117.1° - 118.5°. In the meta substituted benzoyl isothiocyanates the –CONCS group is perpendicular to the phenyl residue. The results are discussed from the point of view of the electron distribution and dipole moments of the compounds studied.

N,N-Linked biazoles. III. MNDO calculations on the conformation of N,N-linked biazoles and their quaternary salts

1984 ◽  
Vol 62 (4) ◽  
pp. 687-695 ◽  
Author(s):  
Maria Luisa Castellanos ◽  
Santiago Olivella ◽  
Nuria Roca ◽  
Javier De Mendoza ◽  
José Elguero
Keyword(s):  
Electronic Properties ◽  
Excellent Agreement ◽  
Theoretical Study ◽  
Dipole Moments ◽  
Mndo Method ◽  
Quaternary Salts ◽  
Mndo Calculations ◽  
Full Optimization ◽  
Experimental Values ◽  
Orthogonal Form

A theoretical study of fourteen N,N-linked biazoles has been carried out using the MNDO method with full optimization of the geometries. The variation of energy as a function of the conformation around the central N—N bond shows in all cases the higher stability of the orthogonal or near-orthogonal form. The contribution of the three main types of "ortho" interactions [Formula: see text] and the effect of quaternization have been evaluated. Of the electronic properties calculated, one must emphasize the excellent agreement of dipole moments with experimental values.

Dipole Moments of meta and para Substituted Benzoyl Isothiocyanates

1993 ◽  
Vol 58 (2) ◽  
pp. 378-384 ◽  
Author(s):  
Ivan Danihel ◽  
Gejza Suchár
Keyword(s):  
Dipole Moments ◽  
Vector Addition ◽  
Mndo Calculations ◽  
Benzoyl Isothiocyanates ◽  
Confirmation Analysis

For a series of meta and para substituted benzoyl isothiocyanates, the dipole moments were determined experimentally and calculated by vector addition of the bond and group dipole moments. Confirmation analysis revealed the preference of the synclinal conformation (τ ∀ 60°), which emerges from the rotation about the C(7)-N bond. MNDO calculations were also performed for the compounds, and the dipole moments obtained were compared with those from the above procedure.

Conformation and electronic structure of aromatic chloroformates

1987 ◽  
Vol 52 (4) ◽  
pp. 970-979 ◽  
Author(s):  
Otto Exner ◽  
Pavel Fiedler
Keyword(s):  
Electronic Structure ◽  
Oxygen Atom ◽  
Strong Interaction ◽  
Electron Distribution ◽  
Room Temperature ◽  
Functional Group ◽  
Dipole Moments ◽  
Carbonyl Oxygen ◽  
Nonpolar Solvents ◽  
Single Method

Aromatic chloroformates Ib-Ie were shown to exist in the ap conformation, in agreement with aliphatic chloroformates, i.e. the alkyl group is situated cis to the carbonyl oxygen atom as it is the case in all esters. While 4-nitrophenyl chloroformate (Ie) is in this conformation in crystal, in solution at most several tenths of percent of the sp conformation may be populated at room temperature and in nonpolar solvents only. A new analysis of dipole moments explained the previous puzzling results and demonstrated the impossibility to determine the conformation by this single method, in consequence of the strong interaction of adjoining bonds. If, however, the ap conformation is once proven, the dipole moments reveal some features of the electron distribution on the functional group, characterized by the enhanced polarity of the C-Cl bond and reduced polarity of the C=O bond. This is in agreement with the observed bond lengths and angles.

scholarly journals СОФІЯ ДЛЯ АВІА

2019 ◽  
pp. 87-96
Author(s):  
А. Л. Свящук
Keyword(s):  
System Theory ◽  
Political System ◽  
Point Of View ◽  
Aircraft Industry ◽  
Philosophical Foundations ◽  
Black Swans ◽  
The World ◽  
Non Linear ◽  
Probabilistic Nature

In the time when the basic formulas and approaches of the aircraft industry are based on the principles of classical science, the nature of the observed phenomena seems non-linear. Such phenomena as turbulence, flutter, buffering, disruption of the air flow can be explained by means of synergetics and system theory in the context of the post-non-classical paradigm. However, a certain contradiction can be observed: non-linear phenomena are explained by linear traditional science. That is why many formulas of aerodynamics and strength have a large empirical part. Therefore, it becomes necessary to revise the philosophical foundations of most approaches and the overall picture of the world as a whole. The use of the concepts of synergetics and system theory allows us to describe more accurately certain phenomena in aviation, which ultimately will lead to the creation of more efficient and safer aircraft. For example, we can design our aircraft not only as a complex system, but also as part of other complex systems, evaluating its effectiveness from the point of view of more ambitious and higher levels, predicting its operation and modernization in the changing conditions of the socio-political system. Moreover, the very nature of engineering creativity based on synergistic approaches will become more efficient and effective by increasing the intensity of aviation thought. Therefore, understanding the role of chance, the effect of emergence will allow us to be prepared for many surprises and black swans and also be wary about our knowledge, assessing their probabilistic nature.

Data Mining for Model Identification

2011 ◽  
pp. 438-444
Author(s):  
Diego Liberati
Keyword(s):  
Mathematical Model ◽  
New Technologies ◽  
A Priori ◽  
Large Data ◽  
Point Of View ◽  
The Other ◽  
Gene Expressions ◽  
Other Hand ◽  
Hybrid Dynamics ◽  
Non Linear

In many fields of research, as well as in everyday life, it often turns out that one has to face a huge amount of data, without an immediate grasp of an underlying simple structure, often existing. A typical example is the growing field of bio-informatics, where new technologies, like the so-called Micro-arrays, provide thousands of gene expressions data on a single cell in a simple and fast integrated way. On the other hand, the everyday consumer is involved in a process not so different from a logical point of view, when the data associated to his fidelity badge contribute to the large data base of many customers, whose underlying consuming trends are of interest to the distribution market. After collecting so many variables (say gene expressions, or goods) for so many records (say patients, or customers), possibly with the help of wrapping or warehousing approaches, in order to mediate among different repositories, the problem arise of reconstructing a synthetic mathematical model capturing the most important relations between variables. To this purpose, two critical problems must be solved: 1 To select the most salient variables, in order to reduce the dimensionality of the problem, thus simplifying the understanding of the solution 2 To extract underlying rules implying conjunctions and/or disjunctions between such variables, in order to have a first idea of their even non linear relations, as a first step to design a representative model, whose variables will be the selected ones When the candidate variables are selected, a mathematical model of the dynamics of the underlying generating framework is still to be produced. A first hypothesis of linearity may be investigated, usually being only a very rough approximation when the values of the variables are not close to the functioning point around which the linear approximation is computed. On the other hand, to build a non linear model is far from being easy: the structure of the non linearity needs to be a priori known, which is not usually the case. A typical approach consists in exploiting a priori knowledge to define a tentative structure, and then to refine and modify it on the training subset of data, finally retaining the structure that best fits a cross-validation on the testing subset of data. The problem is even more complex when the collected data exhibit hybrid dynamics, i.e. their evolution in time is a sequence of smooth behaviors and abrupt changes.

scholarly journals Bringing it all together

2005 ◽  
Vol 9 (1/2) ◽  
pp. 3-14 ◽  
Author(s):  
J. C. I. Dooge
Keyword(s):  
Water Balance ◽  
Water Molecule ◽  
Conceptual Models ◽  
Hydrological Cycle ◽  
Point Of View ◽  
Deterministic Analysis ◽  
Hydrologic Processes ◽  
Complex Processes ◽  
Non Linear ◽  
Global Water

Abstract. The various elements of the hydrological cycle are discussed in outline from the point of view of making progress in analysis through appropriate simplification of these complex processes. Parallels between stochastic and deterministic analysis and between linear and non-linear conceptual models are referred to. The emphasis is on similarities and contrasts between the analysis of hydrologic processes over the range of scales from the water molecule to the global water balance.

Advantages of Spectrally Analyzed Data: Stochastic Models for Automotive Measured Parameters

2014 ◽  
Vol 1036 ◽  
pp. 493-498 ◽  
Author(s):  
Radu Vilău ◽  
Marin Marinescu ◽  
Octavian Alexa ◽  
Florin Oloeriu ◽  
Marian Truta
Keyword(s):  
Dynamic Models ◽  
Real Life ◽  
Stochastic Approach ◽  
Angular Speed ◽  
Point Of View ◽  
Mechanical Parameter ◽  
Complete Analysis ◽  
Measured Parameter ◽  
Useful Signal ◽  
Non Linear

The paper deals with a new approach in data analysis of a measured mechanical parameter. The classic approach is mainly based on the deterministic statistics that cant cover the whole field of a complete analysis. The stochastic approach, to be used in this paper, offers far more information about the mechanical parameter and can take into account the non-linearity of the signal, eventually, the mechanical parameter itself. Starting from the point of view that, in real life, there is no steady evolution of any parameter, we decide to take into account the importance of the non-linear components of any signal. After e thorough investigation, we hope we could make the difference between the noise, as non-linear components of the measured parameter, and the useful non-linear components (e.g. important shocks, typically met within a vehicles transmission). Using the stochastic modeling procedures, we aimed at issuing comprehensive, accurate and valuable dynamic models of the phenomenon. These models cam be used in a large variety of situations, from describing the process, to evaluating the health of a mechanical system and to controlling a real-time process based on the pre-set models (previously drawing a map of the systems normal behavior and permanently assessing the deviation from it and acting accordingly). The data were measured within the transmission system of a military vehicle. Specifically, we have gathered information about torque and angular speed of different shafts of the driveline. As everybody knows, the power flows within any vehicles transmission in transient modes mainly and it is accompanied by plenty of noise. It is rather challenging to separate (filter) the useful signal form the noise but, on the other hand, it is the only way to achieve useful data. Therefore, a spectral analysis is a must, but not the conventional one, which has its drawbacks, but a multi-spectral one, which is able to insulate the noise. Moreover, starting from the analysis developed with this method, mathematical models, both in discrete and continuos time can be achieved. It is easy to notice that the models that we have achieved are featured by a very good accuracy. We could push the data processing even further, getting generalized models that provide the needs we have mentioned before, with respect to the mapping of a normal (averaged) behavior of a system, to be used in controlling procedures.

scholarly journals Dynamic Performances of Foil Bearing Supporting a Jeffcot Flexible Rotor System Using FEM

Lubricants ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 14
Author(s):  
Benyebka Bou-Saïd ◽  
Mustapha Lahmar ◽  
Ahcène Mouassa ◽  
Bachir Bouchehit
Keyword(s):  
Dynamic Behavior ◽  
High Speed ◽  
Point Of View ◽  
Flexible Rotor ◽  
Auxiliary Power ◽  
Partitioned Approach ◽  
Non Linear ◽  
Auxiliary Power Units ◽  
Dynamic Performances ◽  
Air Film

Aerodynamic bearings have received considerable attention in recent decades and are increasingly being used in applications where high speed, low loads and high precision are required. Aerodynamic applications mainly concern auxiliary power units (APU) and air-conditioning machines (ACM). From the industrial point of view, the static and dynamic characteristics of these bearings rotating at very high speed must be determined. According to the literature, studies carried out on this type of bearing consider the elastic deformations of the foils due to the pressure generated in the air film. The linear approach is from time to time adopted for the prediction of the dynamic behavior of these bearings, which is not always justified. This paper aims to present a step towards a better mastery of the non-linear dynamic behavior of a flexible rotor-air bearing system. We will focus on finite element modeling (FEM) of the non-linear isothermal elasto-aerodynamic lubrication problem in the case of a radial bearing operating in a dynamic regime. We will present the effects of rotational speed, unbalance eccentricity, and rotor mass on the non-linear response of rigid and compliant bearings. We use a partitioned approach which treats fluid and structure as two computation domains solved separately; reducing the development time needed for a monolithic code which is difficult to manage when the geometries or the physical properties of the problem to be treated become complex.

MNDO calculations for some allotropes, hydrides, and oxides of phosphorus

1984 ◽  
Vol 62 (2) ◽  
pp. 341-347 ◽  
Author(s):  
N. Colin Baird
Keyword(s):  
Molecular Orbital ◽  
Strain Energy ◽  
Mndo Method ◽  
Molecular Orbital Calculations ◽  
Mndo Calculations

Molecular orbital calculations by the MNDO method are reported for some allotropes, hydrides, and oxides of phosphorus. The aim of the study is to test further the ability of MNDO to reproduce the energetics of PP, PH, and PO bonds, and to apply MNDO to interesting problems in the chemistry of such systems. Different isomers of P4, P6, and P8 are considered, as well as ions of P3, P5, and P7. The method is found to overestimate strain energy in three-membered rings, and to underestimate the strength of three-electron PP bonds. The strength of PO π bonds apparently also is overestimated. Possible isomers of P2O2 and P2O3 are discussed.

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