Resilient Elements Research Articles

Quantifying Road-Network Robustness toward Flood-Resilient Transportation Systems

Amidst sudden and unprecedented increases in the severity and frequency of climate-change-induced natural disasters, building critical infrastructure resilience has become a prominent policy issue globally for reducing disaster risks. Sustainable measures and procedures to strengthen preparedness, response, and recovery of infrastructures are urgently needed, but the standard for measuring such resilient elements has yet to be consensually developed. This study was undertaken with an aim to quantitatively measure transportation infrastructure robustness, a proactive dimension of resilience capacities and capabilities to withstand disasters; in this case, floods. A four-stage analytical framework was empirically implemented: (1) specifying the system and disturbance (i.e., road network and flood risks in Chiang Mai, Thailand), (2) illustrating the system response using the damaged area as a function of floodwater levels and protection measures, (3) determining recovery thresholds based on land use and system functionality, and (4) quantifying robustness through the application of edge- and node-betweenness centrality models. Various quantifiable indicators of transportation robustness can be revealed; not only flood-damaged areas commonly considered in flood-risk management and spatial planning, but also the numbers of affected traffic links, nodes, and cars are highly valuable for transportation planning in achieving sustainable flood-resilient transportation systems.

Green Areas as a Framework for Ensuring the Resilient of Cities

The article is devoted to the assessment of one of the settlements resilient elements - green areas. It is the settlements greenery that fulfill a huge complex of ecosystem environmental services and functions. Several definitions of the settlement’s resilient are given. Further development of this scientific area is includes city resilient profiling and is carried out to compilation the object passport. The method of systematic analysis was applied to field data of structural features and functional zoning of cities in Russia and abroad. It allows us to identify the possibilities of green areas for determination of settlement resilient. The article gives a general view of relevant and up-to-date classification of green areas, which consists of 4 categories and 30 types. Each greening object is evaluated according to the author’s methodology, which includes an assessment of 31 indicators (e.g. debris on the land, area of disturbed land, the presence of unique species, the intensity of the load at survey time, etc.) Each greening object is evaluated according to the author’s methodology, which includes an assessment of 31 indicators (e.g. debris, area of disturbed land, the presence of unique species, the intensity of the load at survey time, etc.) and estimation of six classes of hemerobicity from normal to catastrophic. The total score of these indicators is the coefficient of the environmental situation. With this coefficient, it is possible: to assess the state; compare dynamics and objects, carry out remedial actions to reduce the class of hemorrhage and analyze the effectiveness of these actions. This indicator is a convenient tool for city logistics decisionmakers and public environmental organizations.

Changes in pastoral mobility in a semi-arid montane region of South Africa: The role of policy and legislation

Legislation and policy are key tools used by governments to change the socio-economic and political landscape of agrarian systems with consequences for mobile pastoralism. This study used the social-ecological systems framework to examine how pastoral mobility in the semi-arid, montane communal rangeland in South Africa adapted to the changing socio-political landscape. It analysed the impact of apartheid and democratic era legislation and policies over the past 70 years. Apartheid legislation promoted betterment planning and the privatisation of communal lands by awarding access to most of the grazing areas to a few wealthier pastoralists. This led to increased stocking densities and further restriction of herd mobility when the majority of herds were restricted to fewer grazing camps. Democratic era land reform policies continue to advocate for the modernisation and sedentarisation of pastoral practices. The persistence of mobility among livestock keepers despite discriminatory policy interventions suggests that this is a particularly resilient and necessary element of their practices. We argue that agricultural legislation and policies regarding livestock farming should promote landscape connectivity to allow mobile pastoralists to access variable resources. Connected landscapes should be viewed as alternative ways to modernising pastoralism and these should prevent elite capture when the land is subdivided.

EQUATION OF FLYWHEEL MOVEMENT IN AMORTIZED GIMBAL AND THEIR ANALYSIS

The article examines the transport system with flywheel engine, which is increasingly used in technology. It is an ecologically clean energy source with a high specific power. It is reliable and durable.
 The mechanical system occupies an intermediate place between the gyroscope and the flywheel, which rotates in rigidly fixed supports. It is necessary to conduct the row of researches on vibrofirmness for creation of such mechanical systems, to estimate them dynamic properties and to give out recommendations on creation of transport vehicles with the inertia stores of energy. Dependences of system kinetic and potential energy changes, Rayleigh function was brought by researchers. Damping of supports resilient elements was taken into account. Equalizations of the mechanical system motion were gotten. The analysis of fly-wheel motion was conducted and influence of equalizations nonlinear members on firmness of the mechanical system is conducted. The change of fly-wheel motion frequencies with depending on the parameters of the mechanical system was certain and its fitness for the practical use was appraised. Dependences of vibrations frequencies changes on the angulator of fly-wheel were gotten.
 It was set that frequency of nutation at the increase of angulator of fly-wheel grows, and frequency of recession diminishes. Frequency of nutation with the increase of resilient elements inflexibility of supports grows also and the oscillations of the flywheel and the parameters of the mechanical system are interrelated.

Laboratory experimental study of contact interaction between cut shells and resilient bodies

The study presented herein describes promising designs of shell vibration isolators. The feature of the proposed designs is the cut thin-walled shell usage as the main bearing link. These resilient elements have high load capacity and, on the other hand, can provide the desired level of damping. From the point of view of mechanics, shell resilient elements are considered as the deformable systems with dry friction. When simulating these systems, structurally nonlinear non-conservative mixed contact issues of cut shell – resilient body frictional interaction arise. In order to take into account all essential options of the aforementioned issues and specify shell resilient element peculiarities of behavior under operational loads, the authors used the method of laboratory experiments for research. We considered two different contact systems. The first one is a cylindrical shell cut along its generatrix, which contacts a deformable filler. The second system is a cylindrical shell with several incomplete slots interacting with the elastic filler. The stress state and radial displacements of the shells, pliability of the resilient elements, and energy dissipation in the contact systems were time-tracked. As a result, we obtained relations for monitored options of the contact bodies and deformation diagrams for different physical-mechanical and geometrical options of the systems It was found that for a fixed cycle asymmetry coefficient with an increase in the friction coefficient between the shell and the filler, the amount of energy dissipated per cycle gradually decreases. The idea of optimizing shell vibration protection devices according to the criterion of maximum absorption of energy from external influences by determining the required tribological properties of contacting pairs is declared.

An Analysis of the Modern South Arabian Languages as ‘Islamic Languages’

Abstract The Modern South Arabian languages (MSAL) are seldom mentioned in Islamic studies, as they never served as a literary vehicle. They began to be written only very recently, mainly in text messages, and their use is confined to the domestic environment and oral poetry. Despite this, the MSAL fall neatly within Bausani’s concept of “lingua islamica”: firstly, they have been influenced by an Arabic superstratum since time immemorial, which left numerous traces in their lexis and, to a lesser extent, in other linguistic domains. Secondly, their speakers embraced Islam in the course of a slow but steady process, which began with the wars of apostasy (632-33 CE) and was still ongoing in mid-20th century. Hence, the Islamic culture, conveyed by their Arabic-speaking neighbours, whom they felt as more prestigious, exerted an enormous pressure on the cultural setting of MSAL speakers. Additionally, and in contrast with other Islamic languages, virtually every speaker of a MSAL is proficient in Arabic, and has been so for at least five centuries. In light of the above-mentioned facts, this study describes the extent to which the MSAL can be considered Islamic languages, by looking at their phonetics, morphology, syntax and lexis through the lens of Bausani’s framework. The conclusions show that the MSAL retain remarkably resilient native elements which co-exist with likewise strong Arabic/Islamic elements in a culturally and linguistically functional system.

ДИНАМІКА КОРПУСУ ГУСЕНИЧНИХ МАШИН ІЗ НЕКОНСЕРВАТИВНОЮ СИЛОВОЮ ХАРАКТЕРИСТИКОЮ ПІДВІСКИ

Дана стаття присвячена вивченню нелінійної математичної моделі динаміки гусеничного транспортного засобу. При моделюванні коливань корпусу гусеничного транспортного засобу на базі лінійних та квазілінійних (лінеаризованих) моделей характеристики відновлюючої сили пружних елементів із достатнім степенем точності відображають коливання корпусу для невеликих деформацій торс іонів, тобто руху бойової гусеничної машини пересіченою місцевістю із відносно невеликими нерівностями. Для значних їх деформацій побудовані відповідні розрахункові моделі не в повній мірі відображають динамічний процес руху. Використання нових матеріалів при виробництві торсионів із динамічними пружними властивостями потребують уточненого підходу до побудови нелінійних математичних моделей динаміки руху зразків бронетанкового озброєння та їх базових машин. При побудові математичної моделі було розглянуто тільки вертикальні коливання корпусу гусеничного транспортного засобу під впливом на нього нелінійної пружної сили торсіонів, яка залежить від деформації всіх торсионів та швидкості їх реакції.
 Основні характеристики коливань корпусу було визначено в залежності від співвідношень між величинами нелінійної відновлюючої сили і росту амплітуди коливань. При побудові математичної моделі вважалось, що технічна характеристика демпферних пристроїв системи підресорювання бойової машини залежить від швидкості переміщення корпусу.
 Результати показують, що із ростом амплітуди коливань власна частота може зростати, спадати і навіть залишатись сталою, що безумовно необхідно враховувати при проектуванні систем підресорювання нових або модернізації існуючих гусеничних бойових машин,тому що закладені раціональні технічні рішення у їх підвіску призведе до зменшення впливу пересіченої місцевості на корпус, захисту особового складу, вантажів та спорядження від надмірних навантажень.

Systemic preconditions and ontological modeling for peri-urban communities

PurposeThis research presents an ontological model, to communicate the impact of dynamic preconditions for peri-urban communities. As such, this paper approaches perturbation communities as social-complex-adaptive-systems.Design/methodology/approachPrevious assessment of dynamic preconditions have typically been based on top-down approaches. Through the lens of social-complex-adaptive and systemic design approaches (requiring a range of different disciplines), this work focuses on providing a broader view towards periurban research. The methodological approach involved academic literature, fieldwork observations, in-depth discussions with community, government, experts and research groups, focusing on a region called “Xochimilco” on the outskirts of Mexico City, a unique pre-Hispanic, Aztec ecosystem. This evolving man made agricultural/ecological structure of island plots, still provides environmental services to Mexico City. This region provides the basis of the research and subsequent ontological model. Ontology, in this instance, refers to the nature of being within a range of constraining dynamic forces relating to resilient behaviors of the current Xochimilco perturbation ecosystem.FindingsXochimilco can be considered as a longitudinal phenomenon that contributed to the understanding of observable resilient and precondition elements between the past and present of a living complex-adaptive-system.Practical implicationsThe research has provided a better understanding of community resilience through preconditions, contributing towards preparation of environmental change and future urbanization. To this end, the research focused on visualizing key dynamics elements for communities attempting to absorb new urban conditions (being continuously pushed into it).Originality/valueThe outcomes of this research have provided specific systemic, bottom up approaches with ontological modeling to assist with visualizing and understanding intangible dynamic conditions that impact high complex areas of perturbation regions.

An Efficient Experimental Methodology for the Assessment of the Dynamic Behaviour of Resilient Elements.

The assessment of the dynamic behaviour of resilient elements can be performed using the indirect method as described in the standard ISO 10846-3. This paper presents a methodology for control the error on the estimation of the frequency response functions (FRF) required for the application of the indirect method when sweep sine excitation is used. Based on a simulation process, this methodology allows for the design of the sweep sine excitation parameters, i.e., the sweep rate and the force amplitude, to control three types of errors associated to the experimentally obtained FRF in the presence of background noise: a general error of the FRF in a selected frequency range, and the errors associated to the amplitude and the frequency of the FRF resonance peak. The signal processing method used can be also tested with this methodology. The methodology has been tested in the characterisation of two different resilient elements: an elastomer and a coil spring. The simulated error estimations has been found to be in good agreement with the errors found in the measured FRF. Furthermore, it is found that for large signal-to-noise ratios, both sweep rate and force amplitude significantly affect the FRF estimation error, while, for small signal-to-noise ratios, only the force amplitude can control the error efficiently. The current methodology is specially interesting for laboratory test rigs highly used for the dynamic characterisation of resilient elements which are required to operate efficiently, since it can be used for minimising test times and providing quality assurance. Moreover, the application of this methodology would be specially relevant when characterisation is done in noisy environments.

The legacies of 1945: The evolutions of European civic morality

ABSTRACT This article explores the widespread use of the ‘lessons’ of the era of the Second World War in Europe since 1945. This usage proved to be a resilient element of European cultural values, especially in Western Europe during the era of the Cold War. However, with the emergence of a more diverse and pluralist Europe since 1989, so this form of civic morality has been replaced by new narratives of the war years, and of the twentieth century as a whole. These indicate changes not only in historical perspectives but also in the structures of civic morality.

A Novel Approach to the Analysis of Under Sleeper Pads (USP) Applied in the Ballasted Track Structures.

The present paper is dedicated to the analysis of under sleeper pads (USP), which are resilient elements used in ballasted track systems as vibration isolators. Four types of USP are considered. The authors present the results of laboratory tests, which are then used as input values for the finite element (FE) and mechanical model of the structure. A special focus is put on the description of an original four-degree-of-freedom (4DoF) mechanical model of the system that includes a fractional rheological model of USP. Using the proposed approaches, the dynamic characteristics of under sleeper pads are determined, and conclusions on vibration isolation effectiveness are drawn.

The Use of Under Sleeper Pads to Improve the Performance of Rail Tracks

In recent years, with the growing demand for both passenger and freight mobility, faster and heavier rail traffic has been the norm rather than the exception in many countries. As a result, track geometry and the safety of ballasted rail tracks have been adversely affected, leading to exacerbated maintenance costs. Increased stresses in granular foundation induce progressive track degradation, which can result in excessive vertical and lateral deformation, ballast and subballast fouling and impeded drainage. These effects tend to be more severe at specific locations, such as bridges, level crossings and tunnels (i.e. over stiff subgrade). Finding an economical strategy to mitigate ballast degradation has been a challenging task for practitioners, and the inclusion of energy-absorbing rubber pads underneath the sleepers (under sleeper pads—USPs) to minimise track damage is an attractive solution. This paper presents a laboratory study conducted at the University of Wollongong to investigate the use of USPs as resilient elements in ballasted rail tracks involving a stiff subgrade. Test results have shown a significant improvement in track performance resulting from the use of USPs, whereby it is demonstrated that ballast damage induced by the applied cyclic loads can be reduced due to the favourable damping characteristics of these rubber pads. A significant attenuation in particle breakage was observed along with a reduction in both the vertical settlement and lateral movement of the ballast layer, thereby suggesting that USPs can be an effective means of improving the stability and serviceability of the track system.

A novel approach to characterize the magnetic field and frequency dependent dynamic properties of magnetorheological elastomer for torsional loading conditions

Magnetorheological elastomers (MRE) are potential resilient elements to improve the operating frequency range of a vibration isolator. The field-dependent characterization of MRE properties for varying input frequencies under lateral shear conditions has been well researched in past studies. In the present study, a novel approach to assess the magnetic field dependent rheological properties of magnetorheological elastomers under dynamic torsional loading is presented. Field and frequency-dependent properties are estimated from the dynamic blocked transfer stiffness method specified by ISO 10846. Viscoelastic properties represented in-terms of complex torsional stiffness and loss factor are estimated from the Lissajous curves within the linear viscoelastic (LVE) limit. Experiments are performed at a frequency range of 10 Hz–30 Hz under a constant input angular displacement. Magnetic field sensitive characteristics of MRE are evaluated under the field produced by a custom-made electromagnet. The results reveal a strong influence of field dependent variations on the complex stiffness in comparison with the input frequency. Variations observed in the loss factor suggests a dominance of the imaginary part of the complex stiffness on the energy dissipation. The reduced field induced enhancements in the complex stiffness are interpreted from the Magneto-static and structural based numerical simulations using ANSYS 19.1.

Resilient Element Attached Under the Concrete Sleepers to Improve the Rail Track Performances

Resilient Element Attached Under the Concrete Sleepers to Improve the Rail Track Performances

Characterization of resilient mounts for marine diesel engines: Prediction of static response via nonlinear analysis and response surface methodology

The paper describes an experimental procedure to find the optimal values of the coefficients of the Yeoh hyperelastic material model for a resilient mounting element for marine diesel engines. The quasi-static implicit finite element simulation of the resilient mount deformation under an increasing load is matched with the force-displacement curve of the element acquired via laboratory tests. A response surface analysis is then performed to create a predictive model. This allows to find the best values of the Yeoh coefficients and assess their importance in the predictive equation. With a limited number of runs it is possible to obtain a finite element model that simulates accurately the static deformation of the resilient mounting element over the entire loading range.

Modeling and dynamic characterization of nonlinear non-smooth aeroviscoelastic systems

Abstract In this work, viscoelastic materials are adopted for handling aeroelastic features of typical section models with three degrees-of-freedom, which present non-smooth, free-play type nonlinearities in their control surface. A rotational viscoelastic damper is added to the resilient element associated to the control surface motion of the typical section. Equations of motion are derived accounting for the viscoelastic damper dependence on frequency and temperature. For this, a fractional derivatives-based viscoelasticity constitutive law is considered. Aerodynamic forces are introduced based on linear potential unsteady aerodynamics accounting for arbitrary airfoil motions. The aeroelastic behavior is investigated through time domain simulations, from which bifurcation diagrams are constructed. Numerical results show that the addition of viscoelastic damping can increase the flutter speed noticeably and reduce the amplitudes of limit cycle oscillations for the system under consideration. Another observed benefit provided by the viscoelastic damper is that undesirable subcritical behavior for the bifurcation onset can be eliminated or modified to have a supercritical character. The influence of temperature on the aeroviscoelastic behavior is also investigated. Using the proposed strategy, nonlinear instabilities can be controlled, improving the safety margins of aeroelastic systems.

Calculation of parameters for a resilient element of a flat-belt Continuously Variable Transmission

A design approach of mechanical systems with adaptation property to actual parameters is developed. In particular, a design of a flat-belt Continuously Variable Transmission (CVT) with a variable transfer function depending on the level of a transformed power flow is proposed. This is achieved by means of a control chain, built in directly in auto CVT’s pulley. It is shown that if the control chain is built in both CVT’s pulleys, then in a broad range of external loading change, the chain can be executed on the basis of resilient elements with a linear characteristic. It is shown that if the control chain is built in both CVT’s pulleys, then in a broad range of external loading change, the chain can be executed on the basis of resilient elements with a linear characteristic.

DESIGNING RESILIENT ROOF SYSTEMS

Recent powerful climate storms in the USA have the government discussing the need for resilient buildings: Buildings that can withstand severe storms, provide life safety and be quickly repaired. A building’s roof is often the first line of defense in the changing climate conditions with its catastrophic natural disasters. The roof, if designed properly, can mitigate the impacts of these emergencies and allow a building to withstand and recover from the disruption caused. Resilience is increasingly being viewed as an important performance objective for governmental, educational, commercial and industrial construction. Interest in resiliency is high and is being actively discussed at all levels of the building industry: Governmental, Codes and Standards and Trade Organizations (ASTM, Resilient). This paper will review key resilient roof system elements that need to be considered by roof system designers: Best design and detail practices for roofing to achieve resiliency. The needed level of design and detailing will be reviewed. Recommendations to achieve resilient roof systems will be provided.

Functional survivability analysis of structurally complex technical systems

Aim. The paper analyzes the functional survivability of structurally complex technical systems. This approach is the evolution of the structural survivability paradigm, when the system/element failure criterion is binary. The paper shows that given a wide variety of probabilistic scenarios of adverse effects (AE) on a system, an invariant model kernel is identified that is responsible for the interpretation of functional redundancy. The aim is to identify the proportion of retained operable states within the acceptable computational time, when the fixed number u of elements is disabled as the result of AE. In this case the analysis of survival law is conducted at the confluence of functional redundancy analysis and probabilistic AE models of arbitrarily wide variety. Methods . A technical system is considered a controllable cybernetic system equipped with specialized survival facilities (SF). System survivability analysis uses logic and probabilistic methods, as well as the results of the combinatorial theory of random allocation. It is assumed that: a) AE are localized and single (one effect affects exactly one element); b) each of the system’s elements has a binary logic (operability – failure) and zero resilience, i.e. destruction after one effect is guaranteed. Subsequently this assumption is generalized for the case of r-fold AE and L-resilient element. Results. The paper reconstructs a number of variants of the destruction law and survivability functions of technical systems. It is identified that those distributions are based on prime and generalized Morgan numbers, as well as Stirling numbers of the second kind that can be recovered using the simplest recurrence formulas. While the assumptions of the mathematical model are generalized for the case of nr-fold AE and L-resilient elements, the generalized Morgan numbers involved in the estimation of the destruction law are identified using the random allocation theory by means of n-fold differentiation of the generating polynomial. In this case it does not appear to be possible to establish a recursive relation between the generalized Morgan numbers. It is shown that under homogeneous assumptions regarding the survivability model (equally resilient system elements, equally probable AEs) in the correlation kernel for the system survivability function, regardless of the destruction law, is the functional redundancy vector F(u, e ), where u is the number of affected elements, e is the system’s limiting efficiency criterion, below which its functional failure is diagnosed, F(u, e ) is the number of system states operable in terms of e under u failures (destructions) of its elements. Conclusions. Point models of survivability are an excellent tool of express analysis of structurally complex systems and tentative estimation of survivability functions. The most simple assumptions of structural survivability can be generalized in cases when the system’s operability logic is not binary, yet is associated with the level of system operation efficiency. In this case we must speak of functional survivability. The PNP computational complexity of the survivability evaluation problem does not allow solving it by means of a simple enumeration of the system states and AE variants. Ways must be found of avoiding simple enumeration, e.g. by using conversion of the system operability function and its decomposition by means of generalized logical and probabilistic methods.

Dynamic assessment of nonlinear typical section aeroviscoelastic systems using fractional derivative-based viscoelastic model

Nonlinear aeroelastic systems are prone to the appearance of limit cycle oscillations, bifurcations, and chaos. Such problems are of increasing concern in aircraft design since there is the need to control nonlinear instabilities and improve safety margins, at the same time as aircraft are subjected to increasingly critical operational conditions. On the other hand, in spite of the fact that viscoelastic materials have already been successfully used for the attenuation of undesired vibrations in several types of mechanical systems, a small number of research works have addressed the feasibility of exploring the viscoelastic effect to improve the behavior of nonlinear aeroelastic systems. In this context, the objective of this work is to assess the influence of viscoelastic materials on the aeroelastic features of a three-degrees-of-freedom typical section with hardening structural nonlinearities. The equations of motion are derived accounting for the presence of viscoelastic materials introduced in the resilient elements associated to each degree-of-freedom. A constitutive law based on fractional derivatives is adopted, which allows the modeling of temperature-dependent viscoelastic behavior in time and frequency domains. The unsteady aerodynamic loading is calculated based on the classical linear potential theory for arbitrary airfoil motion. The aeroelastic behavior is investigated through time domain simulations, and subsequent frequency transformations, from which bifurcations are identified from diagrams of limit cycle oscillations amplitudes versus airspeed. The influence of the viscoelastic effect on the aeroelastic behavior, for different values of temperature, is also investigated. The numerical simulations show that viscoelastic damping can increase the flutter speed and reduce the amplitudes of limit cycle oscillations. These results prove the potential that viscoelastic materials have to increase aircraft components safety margins regarding aeroelastic stability.