Dynamic Interaction Analysis of Coupled Axial-Torsional-Lateral Mechanical Vibrations in Rotary Drilling Systems

Maintaining the integrity and longevity of structures is essential in many industries,such as aerospace,nuclear,and petroleum.To achieve the cost-effectiveness of large-scale systems in petroleum drilling,a strong emphasis on structural durability and monitoring is required.This study focuses on the mechanical vibrations that occur in rotary drilling systems,which have a substantial impact on the structural integrity of drilling equipment.The study specifically investigates axial,torsional,and lateral vibrations,which might lead to negative consequences such as bit-bounce,chaotic whirling,and high-frequency stick-slip.These events not only hinder the efficiency of drilling but also lead to exhaustion and harm to the system’s components since they are difficult to be detected and controlled in real time.The study investigates the dynamic interactions of these vibrations,specifically in their high-frequency modes,usingfield data obtained from measurement while drilling.Thefindings have demonstrated the effect of strong coupling between the high-frequency modes of these vibrations on drilling sys-tem performance.The obtained results highlight the importance of considering the interconnected impacts of these vibrations when designing and implementing robust control systems.Therefore,integrating these compo-nents can increase the durability of drill bits and drill strings,as well as improve the ability to monitor and detect damage.Moreover,by exploiting thesefindings,the assessment of structural resilience in rotary drilling systems can be enhanced.Furthermore,the study demonstrates the capacity of structural health monitoring to improve the quality,dependability,and efficiency of rotary drilling systems in the petroleum industry.

Existence of Al2F-7^- in molten MF–AlF3(M = K, Cs) systems as determined by Raman spectroscopy and structural simulation

The molten mixtures of alkali metal fluorides and aluminum fluoride are applied as aluminum electrolytes or brazing fluxes.However,the presence of Al2F-7^-in such molten systems is disputed.In the present study,MF-AlF3(M=K,Cs)systems with molar ratios<1 were studied by in-situ Raman spectroscopy and molecular simulation.The results show that,in addition to AlF6^(3-),AlF5^(2-),and AlF4^-,the systems also contained Al2F-7^-.The characteristic bands in the Raman spectra belonging to Al2F-7^-were located at about 225 cm^-1,315 cm^-1,479 cm^-1,and 720 cm^-1.There are two possible structures of Al2F-7^-,which belong to the D3d and D3hpoint groups.Both of these structures are linear,and their single-point energies were found to differ by only 0.31 kcal/mol.

Auxiliary Software for Defining the Parameters of the Structural Organization of a Complex System

The developed auxiliary software serves to simplify, standardize and facilitate the software loading of the structural organization of a complex technological system, as well as its further manipulation within the process of solving the considered technological system. Its help can be especially useful in the case of a complex structural organization of a technological system with a large number of different functional elements grouped into several technological subsystems. This paper presents the results of its application for a special complex technological system related to the reference steam block for the combined production of heat and electricity.

Linear systems toolkit in Matlab :structural decompositions and their applications

This paper presents a brief description of the software toolbox, linear systems toolkit, developed in Matlab environment. The toolkit contains 66 m-functious, including structural decompositions of linear autonomous systems, unforced/uuseused systems, proper systems, and singular systems, along with their applications to system factorizations, sensor/actuator selection, H-two and H-infinity control, and disturbance decoupling problems.

Effect of structural characteristics distribution on strength demand and ductility reduction factor of MDOF systems considering soil-structure interaction

It is known that structural stiffness and strength distributions have an important role in the seismic response of buildings. The effect of using different code-specified lateral load patterns on the seismic performance of fixed-base buildings has been investigated by researchers during the past two decades. However, no investigation has yet been carried out for the case of soil-structure systems. In the present study, through intensive parametric analyses of 21,600 linear and nonlinear MDOF systems and considering five different shear strength and stiffness distribution patterns, including three code-specified patterns as well as uniform and concentric patterns subjected to a group of earthquakes recorded on alluvium and soft soils, the effect of structural characteristics distribution on the strength demand and ductility reduction factor of MDOF fixed-base and soil-structure systems are parametrically investigated. The results of this study show that depending on the level of inelasticity, soil flexibility and number of degrees-of-freedoms (DOFs), structural characteristics distribution can significantly affect the strength demand and ductility reduction factor of MDOF systems. It is also found that at high levels of inelasticity, the ductility reduction factor of low-rise MDOF soil-structure systems could be significantly less than that of fixed-base structures and the reduction is less pronounced as the number of stories increases.

Control Lyapunov Stabilization of Nonlinear Systems with Structural Uncertainty

This paper deals with global stabilization problem for the nonlinear systems with structural uncertainty. Based on control Lyapunov function, a sufficient and necessary condition for the globally and asymptotically stabilizing the equailibrium of the closed system is given. Moreovery, an almost smooth state feedback control law is constructed. The simulation shows the effectiveness of the method.

Industrial Structural Changes in Hong Kong,China under One Country,Two Systems Framework

Hong Kong has undergone substantial economic transformations and developed into a sophisticated busi- ness and financial center in the Asia-Pacific region, since the return of sovereignty to China as a Special Administrative Region under the One Country Two Systems （OCTS） in 1997. This paper discusses and analyzes the industrial struc- tural changes of Hong Kong in recent decades as well as its future challenges and opportunities, The data and finding reveal that even though Hong Kong will face fierce competition from the Mainland＇s cities as the rise of China, the important role as a bridge between China and the rest of the world wilt brace Hong Kong itself under the OCTS for developing into a service hub for business and trade in the Asia-Pacific region.

Robust stabilization of general nonlinear systems with structural uncertainty

This paper deals with the robust stabilization and passivity of general nonlinear systems with structural uncertainty. By using Lyapunov function, it verifies that under some conditions the robust passivity implies the zero-state detectability, Furthermore, it also implies the robust stabilization for such nonlinear systems. We then establish a stabilization method for the nonlinear systems with structural uncertainty. The smooth state feedback law can be constructed with the solution of an equation. Finally, it is worth noting that the main contribution of the paper establishes the relation between robust passivity and feedback stabilization for the general nonlinear systems with structural uncertainty. The simulation shows the effectiveness of the method.

A STUDY ON THE STRUCTURAL EFFECT OF DOUBLE BRIDGES CONJUGATED SYSTEMS I.CARBONYL-IMINO SYSTEM

The struetural effect of the conjugative system(C)with carbonyl-imino bridges has been studied.The results show that:In the conjugated system(C),there is no electronic absorption peak attributable to the whole system,but there are three π-π* bands each nt which displays chacactecistics of its own independently.These indicate that the two bridges-carbonyl-and-imino-can block the tlanSmlSSion of the conjngative polarization of the whole system,so as to form three segments,this is verified by means of chemical synthesis and degradation.

Independent and Combined Effect of Some Soil Tillage Systems on Nitrogen and Carbon Concentration in Soil Structural Units of Haplic Chernozems

This paper aimed at studying the effect of different types of soil tillage systems on the change of total carbon （C） and nitrogen （N） in the soil structural units of different size after dry structural analysis of soil. The research was carried out in a 6-field rotation system （grain maize-wheat-sunflower-wheat-bean-wheat） at the end of the 2nd rotation. Six out of 24 soil tillage systems were selected; they were applied independently and in combination in the crop rotation. After that, they were compared to the system with constant deep plowing. So a total of seven soil tillage systems were investigated. The selected systems for main soil tillage were the following： plowing （control variant）, disking, cutting, nil tillage （direct sowing）, plowing-disking, plowing-nil tillage, disking-nil tillage. Three depths of 0-10, 10-20 and 20-30 cm were studied, as well as soil structural units were of the following sizes： 〉 10 mm, 10-5, 5-3, 3-1, 1-0.25 mm and 〈 0.25 mm. As a result of systematic implementation of different soil tillage systems, higher N and C concentrations were established by the layers according to constant plowing. Constant disking and its alternation with nil tillage increased the total N concentration with 15.6% and 11.1%, respectively, in comparison with the constant plowing. The same was valid for C concentration in soil, but the highest increase was established in the variants with constant cutting and nil tillage. The exceeding was with 14.0% and 13.2%, in comparison to constant plowing. The redistribution of N and C depending on the structural soil units was most expressed in the 0-10 cm and 10-20 cm layers. The highest amounts of C and N were found in the soil units with size less than 5 mm, mainly in the 〈 0.25 mm fraction. At depth of 20-30 cm, the role of the size of soil structural units for C and N redistribution decreased strongly. The values of C/N ratio were moderate only under the use of constant disking. This index was low under all other soil tillage systems. The correlation of total N with C in soil was high, positive and significant depending on the size of structural soil units and the tillage systems, as average for the investigated factors in this experiment. The minimal tillage and the tillage without turning of soil, used independently and in combination, had the highest contribution to preserving the organic matter in the haplic Chernozems of Dobrudzha region.

Opportunistic maintenance for multi-component systems considering structural dependence and economic dependence

Although opportunistic maintenance strategies are widely used for multi-component systems, all opportunistic mainte- nance strategies only consider economic dependence and do not take structural dependence into account. An opportunistic main- tenance strategy is presented for a multi-component system that considers both structural dependence and economic dependence. The cost relation and time relation among components based on structural dependence are developed. The maintenance strategy for each component of a multi-component system involves one of five maintenance actions, namely, no-maintenance, a minimal maintenance action, an imperfect maintenance action, a perfect maintenance action, and a replacement action. The maintenance action is determined by the virtual age of the component, the life expectancy of the component, and the age threshold values. Monte Carlo simulation is designed to obtain the optimal oppor- tunistic maintenance strategy of the system over its lifetime. The simulation result reveals that the minimum maintenance cost with a strategy that considers structural dependence is less than that with a strategy that does not consider structural dependence. The availability with a strategy that considers structural dependence is greater than that with a strategy that does not consider structural dependence under the same conditions.

An iterative algorithm for analysis of coupled structural-acoustic systems subject to random excitations

This paper analyzes the random response of structural-acoustic coupled systems. Most existing works on coupled structural-acoustic analysis are limited to systems under deterministic excitations due to high computational cost required by a random response analysis. To reduce the computational burden involved in the coupled random analysis, an iterative procedure based on the Pseudo excitation method has been developed. It is found that this algorithm has an overwhelming advantage in computing efficiency over traditional methods, as demonstrated by some numerical examples given in this paper.

Structural Eurocodes Systems (China) Forum Held in Beijing——Construction Standards in China

The Structural Eurocodes Systems, which are developed by the European Committee for Standardization (CEN), have come into trial use in the 28 countries of European Union (EU), and will lay a significant influence on the development of the construction industry and on the international market of construction.

Parameter-dependent vibration-attenuation controller design for electro-hydraulic actuated linear structural systems

The problem of robust active vibration control for a class of electro-hydraulic actuated structural systems with time-delay in the control input channel and parameter uncertainties appearing in all the mass, damping and stiffness matrices is investigated in this paper. First, by introducing a linear varying parameter, the nonlinear system is described as a linear parameter varying （LPV） model. Second, based on this LPV model, an LMI-based condition for the system to be asymptotically stabilized is deduced. By solving these LMIs, a parameter-dependent controller is established for the closed- loop system to be stable with a prescribed level of disturbance attenuation. The condition is also extended to the uncertain case. Finally, some numerical simulations demonstrate the satisfying performance of the proposed controller.

Comparison of adaptive structural damage identification techniques in nonlinear hysteretic vibration isolation systems

Early structural damage identification to obtain an accurate condition assessment can assist in the reprioritization of structural retrofitting schedules in order to guarantee structural safety. Nowadays, seismic isolation technology has been applied in a wide variety of infrastructure, such as buildings, bridges, etc., and the health conditions of these nonlinear hysteretic vibration isolation systems have received considerable attention. To effectively detect structural damage in vibration isolation systems based on vibration data, three time-domain analysis techniques, referred to as the adaptive extended Kalman filter （AEKF）, adaptive sequential nonlinear least-square estimation （ASNLSE） and adaptive quadratic sum-sqnares error （AQSSE）, have been investigated. In this research, these analysis techniques are compared in terms of accuracy, convergence and efficiency, for structural damage detection using experimental data obtained through a series of laboratory tests based on a base-isolated structural model subjected to E1 Centro and Kobe earthquake excitations. The capability of the AEKF, ASNLSE and AQSSE approaches in tracking structural damage is demonstrated and compared.

Reliability Analysis for Offshore Platform Structural Systems

A system reliability estimation method for spatial jacket platforms is developed in this paper. The jacket platform is modeled into three-dimensional assembly of spatial beam and plate elements in Finite Element Method (FEM). The limit failure states correspond to collapse of a series of structural members which are identified by engineering design criteria. In this paper the following aspects are taken into account: the punching shear and buckling failures in member failure modes for the tubular joints and tubular columns respectively; incremental loading approach for establishment of the safety margin equations of system failure; the algorithm of enumerating significant failure modes for the structural systems and other concepts, such as the false failure mode and the virtual limit state. The final work is devoted to the reliability analysis for a practical jacket platform presently put into operation on the Bohai Sea. The computed results shows that method suggested in this paper is feasible and effective for the evaluation of the system reliability of offshore platforms.

Active vibration-attenuation controller design for uncertain structural systems with input time-delay

The problem of active vibration control for uncertain linear structural systems with control forces input timedelay is investigated in this study.First,the original structural equation is converted to a state-space model by utilizing the matrix transformation.Second,according to the obtained model and a special Lyapunov functional,a sufficient condition is achieved for the closed-loop system to be stable with a prescribed level of disturbance attenuation.Then,in terms of solving these linear matrix inequalities（LMIs）,the state-feed controller is achieved to stabilize the structural system with the performance ‖z‖2<γ‖ω‖2.Third,by introducing the rank-1 vector to describe the system uncertainties,the uncertain system description is obtained,and the stabilizing condition is extended to the uncertain case.Finally,examples are given to show the effectiveness of the proposed methods.

ROBUST STABILIZATING FOR A OLASS OF UNOERTAIN NONLINEAR INTEROONNECTED SYSTEMS USING VARIABLE STRUCTURE CONTROL

The robust stabilizating control problem for a class of uncertain nonlinear large-scale systems is discussed. Based on the theory of both input/output (I/O) linearization and decentralized variable structure control (VSC),two-level and decentralized variable structure control laws for this kind of systems are presented respectively,which achieve asymptotically stabilization despite the uncertainties and disturbances. At last,sirnulation of the disturbed two-pendulum system is given to illustrate the feasibility of proposed technique.

ANALYSIS OF STRUCTURAL STYLES OF THE BASIN-RANGE SYSTEMS IN THE CENTRAL CHINA OROGENIC CHAIN OF YANGTZE VALLEY AND THE DYNAMIC MECHANISM

Basin and orogenic belt belong to the same tectonic system which has close connections in spatial distribution and dynamic mechanism.Structural styles analysis of basin－ range system， not only may rebuild basin－ range coupling process and landscape evolution of orogenic belt and its adjacent basin， but also become the foundation in exploring how orogenesis controls landform,climate,resources,energy and environment etc.In the light of geodynamic mechanism,three main types of basin－ range system may be classified,namely,stretch,compression and strike－ slip.In combination with their geotectonic settings and plate movement phases, a comprehensive classification scheme may be educed for structural styles of basin－ range system.Natural disasters and geo－ ecological environment in the Yangtze Valley have been restricted and impressed by crustal movement and Qinling－ Dabie etc.orogenesis since the Mesozoic and Cenozoic.In terms of collocating relation and contacting basin prototype and orogenic belt around the basin for cause of formation, typical structural styles of basin－ range system on the central orogenic chain within the Yangtze Valley consist of coupling Tongbo－ Dabie orogenic belt and Jianghan－ Dongtin fault basin on the northern margin of the central Yangtze landmass， and coupling Qinling－ Daba mountain margin thrust－ faulted orogenic belt and Sichuan foreland basin on the northern margin of upper－ Yangtze landmass.The paper analyzes evolutionary features of two typical structural styles of basin－ range system during syn－ orogenic, late－ orogenic and post－ orogenic stages,and probes into their dynamic mechanism.It is emphasized that,in different stages of basin－ range system of different properties and basin－ mountain transformation process,different structural styles may be formed;and different associations of structural styles can form different types of natural disasters complex and eco－ environment systems.

Attribute Reduction of Hybrid Decision Information Systems Based on Fuzzy Conditional Information Entropy

The presence of numerous uncertainties in hybrid decision information systems(HDISs)renders attribute reduction a formidable task.Currently available attribute reduction algorithms,including those based on Pawlak attribute importance,Skowron discernibility matrix,and information entropy,struggle to effectively manages multiple uncertainties simultaneously in HDISs like the precise measurement of disparities between nominal attribute values,and attributes with fuzzy boundaries and abnormal values.In order to address the aforementioned issues,this paper delves into the study of attribute reduction withinHDISs.First of all,a novel metric based on the decision attribute is introduced to solve the problem of accurately measuring the differences between nominal attribute values.The newly introduced distance metric has been christened the supervised distance that can effectively quantify the differences between the nominal attribute values.Then,based on the newly developed metric,a novel fuzzy relationship is defined from the perspective of“feedback on parity of attribute values to attribute sets”.This new fuzzy relationship serves as a valuable tool in addressing the challenges posed by abnormal attribute values.Furthermore,leveraging the newly introduced fuzzy relationship,the fuzzy conditional information entropy is defined as a solution to the challenges posed by fuzzy attributes.It effectively quantifies the uncertainty associated with fuzzy attribute values,thereby providing a robust framework for handling fuzzy information in hybrid information systems.Finally,an algorithm for attribute reduction utilizing the fuzzy conditional information entropy is presented.The experimental results on 12 datasets show that the average reduction rate of our algorithm reaches 84.04%,and the classification accuracy is improved by 3.91%compared to the original dataset,and by an average of 11.25%compared to the other 9 state-of-the-art reduction algorithms.The comprehensive analysis of these research results clearly indicates that our algorithm is highly effective in managing the intricate uncertainties inherent in hybrid data.