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Paper presents a new way of the structural - topological analysis for the parallel manipulators, with referring to the calculation of mobility (degree of freedom) of complex mechanisms. The parallel manipulators are complex topological structure, having the joints (as kinematical pairs) of various types. The thirty six formulas known in the literature for mobility calculation are grouped in two categories: those for a quick calculation of mobility from the visual inspection of kinematical schema, and the approaches based on rank of the kinematical constraint equations. For the parallel manipulators we present a new formula for mobility calculation in function of the kinematical chains number, considered as the identical legs. [ABSTRACT FROM AUTHOR]

Recently, some existing works have introduced novel way to construct complex networks from embedded time series, which provides new sights into the organizational properties of the time series in phase space. In this paper, we attempt to answer the fundamental question of 'how much information regarding the dynamic property of the original time series can be extracted from these networks.' To this end, we propose a new method for reconstructing time series from the networks. We compare the reconstructed time series from these networks and that from the recurrence plot. We find that these networks contain topological information of the embedded time series to a certain degree. In general, they are more powerful than the recurrence plot method in the reconstruction of embedded time series. In addition, we study a new generalized projective synchronization (GPS) of coupled complex dynamical networks with different sizes via feedback control and impulsive control. Based on the stability analysis of impulsive system, a network synchronization criterion is established. These works may find potential application for secure communication via networks. [ABSTRACT FROM AUTHOR]

Under the operating condition of a solid breeding blanket, the ceramic breeder pebbles applying pebble bed configuration will conduct with complex mechanical behaviors. In this study, the Discrete Element Method (DEM) was adopted to generate randomly packed pebble beds considering the size distribution, particle sphericity and surface friction of breeder pebbles. Based on these discrete packing structures, the cyclic uniaxial compression tests (UCTs) were implemented in the mechanical analysis of the pebble beds. The results indicate that the initial packing behaviors and non-linear stress-strain responses of the pebble beds were highly affected by size distribution, particle sphericity and surface friction of breeder pebbles. Besides, the internal contact forces between the pebbles could be alleviated to some extent through cyclic uniaxial compression tests. After these progressive loading cycles, the pebble beds were strengthened with increasing effective elastic moduli, and the effects of the loading pressure on the elastic moduli of the strengthened pebble beds were estimated. [ABSTRACT FROM AUTHOR]

The design change propagation in a complex product is characteristic of nonlinear, dynamic, and uncertain; its impact analysis becomes challenging. Furthermore, the multiple changes occurring concurrently during the whole design process increase the difficulty of the change propagation analysis. In this article, a new change propagation prediction method based on multi-agent system, especially for multi-variations, is proposed to improve the validity of the change routing paths. As the foundation of the proposed prediction method, a hierarchical network composited of the specific design properties is used to represent the design change analysis model. Based on the discussion of concurrent propagation patterns in the context of multi-variations, the quantitative definition of change propagation impact focuses on two factors: change impact and propagation likelihood. To reduce the subjective measurements estimated through the designer’s experience, the change impact and the propagation likelihood are quantified by evaluating the design specification and mining the design change records, respectively. Based on the quantified change propagation impact, the multi-variation propagation simulation is parameterized and implemented in the platform of NetLogo. To demonstrate the effectiveness of the proposed method, experiments are conducted with one typical scenario. Compared with the classical change propagation methods, the proposed method proves to be valid for analyzing the concurrent change propagation, and the analysis reliability is guaranteed. [ABSTRACT FROM AUTHOR]

Fiber networks encompass a wide range of natural and manmade materials. The threads or filaments from which they are formed span a wide range of length scales: from nanometers, as in biological tissues and bundles of carbon nanotubes, to millimeters, as in paper and insulation materials. The mechanical and thermal behavior of these complex structures depends on both the individual response of the constituent fibers and the density and degree of entanglement of the network. A question of paramount importance is how to control the formation of a given fiber network to optimize a desired function. The study of fiber clustering of natural flocs could be useful for improving fabrication processes, such as in the paper and textile industries. Here, we use the example of aegagropilae that are the remains of a seagrass (Posidonia oceanica) found on Mediterranean beaches. First, we characterize different aspects of their structure and mechanical response, and second, we draw conclusions on their formation process. We show that these natural aggregates are formed in open sea by random aggregation and compaction of fibers held together by friction forces. Although formed in a natural environment, thus under relatively unconstrained conditions, the geometrical and mechanical properties of the resulting fiber aggregates are quite robust. This study opens perspectives for manufacturing complex fiber network materials. [ABSTRACT FROM AUTHOR]

For high-speed robotics dynamic (shaking) force and (shaking) moment balance are important properties to obtain low base vibrations, high precision, and short cycle times, a.o., while for large moving structures such as movable bridges and movable roofs force balance is important for safety and low energy usage. To find applicable solutions, dynamic balance can be considered in the very beginning of the design process by synthesis from principal vector linkages: fundamental kinematic architectures with inherent force balance. Succeeding the already studied open-chain principal vector linkages, this paper introduces the design and analysis of closed-chain principal vector linkages with two approaches. With the proposed open-chain method solutions are obtained by simply closing the chain of an open-chain principal vector linkage. With the proposed method of the mass equivalent principal chain less complex solutions are obtained with consideration of the loop closure relations. Then an open-chain principal vector linkage is closed with an additional element which, with a general mass distribution, is modeled mass equivalently in a new way with two real equivalent masses and one virtual equivalent mass. The results are validated with a dynamic simulation and a grasper mechanism with payload balanced together is shown as application example. [ABSTRACT FROM AUTHOR]

In this study, near-surface geophysical techniques are used to investigate the physical characteristics of the Buyukcekmece landslide (Istanbul, Turkey). The Buyukcekmece landslide has continuous activity at a low velocity and is classified as a complex mechanism. It includes rototranslational parts, several secondary scarps, several landslide terraces, and evidence of two earth flows. It mainly develops in the clayey layers of the Danismen Formation. According to our findings, P-wave velocities ranging from 300 m/s to 2400 m/s do not provide notable discrimination between sliding mass and stable soil. They show variations in blocks reflecting a complex structure. We obtained the S-wave velocity structure of the landslide up to 80 m by combining the analysis of MASW and ReMi. It is clear that S-wave velocities are lower in the landslide compared to those of the stable area. Identical S-wave velocities for the entire area at depths higher than 60 m may point out the maximum thickness of the landslide mass. Resonance frequencies obtained from the H/V analysis of the landslide area are generally higher than those of the stable area. The depths computed by using an empirical relationship between the resonance frequency and the soil thickness point out the failure surfaces from 10 to 50 m moving downslope from the landslide crown area. The resistivity values within the landslide are generally lower than 30 Ω m, i.e., a typical value for remolded clayey debris. The geophysical results reflect an overview of the geological model, but the complexity of the landslide makes it difficult to map the landslide structure in detail. [ABSTRACT FROM AUTHOR]

Rigidity detection is an important tool for structural synthesis of mechanisms, as it helps to unveil possible sources of inconsistency in Grübler's count of degrees of freedom (DOFs) and thus to generate consistent kinematical models of complex mechanisms. One case that has puzzled researchers over many decades is the famous "double-banana" problem, which is a representative counter-example of Laman's rigidity condition formula for which existing standard DOF counting formulas fail. The reason for this is the body-by-body and joint-by-joint decomposition of the interconnection structure in classical algorithms, which does not unveil structural isotropy groups for example when whole substructures rotate about an "implied hinge" according to Streinu. In this paper, a completely new approach for rigidity detection for cases as the "double-banana" counterexample in which bars are connected by spherical joints is presented. The novelty of the approach consists in regarding the structure not as a set of joint-connected bodies but as a set of interconnected loops. By tracking isolated DOFs such as those arising between pairs of spherical joints, rigidity/mobility subspaces can be easily identified and thus the "double-banana" paradox can be resolved. Although the paper focuses on the solution of the double-banana mechanism as a special case of paradox bar-and-joint frameworks, the procedure is valid for general body-and-joint mechanisms, as is shown by the decomposition of spherical joints into a series of revolute joints and their rigid-link interconnections. [ABSTRACT FROM AUTHOR]

This paper investigates a biomechanical aspect of human hand during grasping, using the finite-element method. A realistic three-dimensional finite–element (FE) model of a human hand is developed, including wrist bones, phalanges, soft tissues and skin, reconstructed from medical computed tomography (CT) scan images. Material laws of the literature have been implemented in the model, in order to be able to simulate a simple activity of grasping. In a human design context, this model allows an interesting biomechanical study, which simulates the grasping task in a biofidelic manner. This model is a first step in the modeling of the human hand that can lead to future studies dealing with the interaction of the hand with its environment for the improvement of safety requirements of future products development. [ABSTRACT FROM PUBLISHER]

Diffusion in nanoporous host–guest systems is often considered to be too complicated to comply with such “simple” relationships as Fick's first and second law of diffusion. However, it is shown herein that the microscopic techniques of diffusion measurement, notably the pulsed field gradient (PFG) technique of NMR spectroscopy and microimaging by interference microscopy (IFM) and IR microscopy (IRM), provide direct experimental evidence of the applicability of Fick's laws to such systems. This remains true in many situations, even when the detailed mechanism is complex. The limitations of the diffusion model are also discussed with reference to the extensive literature on this subject. [ABSTRACT FROM AUTHOR]

Aimed to provide a more close-to-reality and rapid calculation method for optimization design of low voltage circuit breaker with complex mechanism, an interruption model is constructed, which can describe the coupling of air blast process with arc model, complex mechanical movement, magnetic field, and electric circuit. The model is based on the non-stationary gas conservation equations, and considers the influence of the chamber structure on the gas dynamics. To realize the interaction between the arc movement and the gas flow simply, on the one hand, the moving electric arc is deemed an energy input source of the chamber gas. On the other hand, the movement equation of the arc considering action of the gas flow is built. With this model, the general principle of the chamber gas flow, arc voltage and current during the interruption process of an actual breaker are calculated and compared with the experiment results. As an application, the influence of the chamber vent size on the arc movement is studied with the model as well. [ABSTRACT FROM AUTHOR]

Generalized Coordinate Partitioning (GCP), a partitioning of the Jacobian matrix, allows for the automatic identification of dependent and independent variables and primary and secondary systems of equations for constrained multibody mechanisms. The GCP method is achieved through the row and column permutations associated with applying Gaussian Elimination with Complete Pivoting (GECP) to the constraint Jacobian matrices. GCP forms the basis of robust and efficient kinematic path planning and solution of dynamic equations of motion, with the potential to achieve orders of magnitude speed up over least squares and iterative methods. Despite these benefits, a significant disadvantage is that the GCP method is numerically expensive. This paper presents a technique to automatically rearrange groups of intersecting kinematic loops into non-overlapping kinematic substructures, which effectively block-diagonalizes the Jacobian Matrix. The method is applied to a hydraulic excavator, an illustrative example of a complex mechanism, and an approximate order of magnitude reduction in floating point operations required to perform the GCP method is demonstrated. Numerical results comparing the run time of the kinematic substructuring technique to sparse matrix methods and full dense GECP are provided. Furthermore, a compact representation of the equations of motion is formulated, accounting for the kinematic substructures identified in the mechanism. [ABSTRACT FROM AUTHOR]

Drawing on previous studies related to the evolutionary aspects of regional innovation systems (RIS), this paper examines how an exogenous shock reduced organizational thinness, fragmentation and lock-in and thereby facilitated path creation and RIS emergence in a peripheral region. A longitudinal case study approach, based on primary data from 39 interviews conducted between 2008 and 2012, is used to investigate how a region was affected by the sudden entry and subsequent activity of a multinational oil company. A multi-level analysis illustrates how this exogenous shock facilitated change at the firm, public authority and macro (regional) levels and thus provides a holistic understanding of the complex mechanisms that underlie regional transformation. The analysis illustrates how the entry of the oil company reduced organizational thinness by stimulating the establishment of external firms. The existing regional actors then managed to reduce their organizational lock-in by adapting their skills and resource bases to new knowledge provided through interfirm relationships (reduced fragmentation), and this reduced organizational lock-in and fragmentation ultimately strengthened the industrial structure and further contributed to regional path creation. A number of innovations were observed, and in combination with the “thickened” institutional structure, this represented the means for an emerging RIS. [ABSTRACT FROM PUBLISHER]

The paper puts forward a complex linkage mechanism with two degrees of mobility and three kinematic loops, which is used for the guiding (suspension and steering) system of the vehicles. The geometric parameters and the coordinates frames that define the mechanical system are presented, as well as the specific kinematic functions. For this complex mechanical system, the angular capability of the ball (spherical) joints is defined by two angles. The equations for these angles have been determined by matrix algebra tools, considering the transformation matrices between the bodies reference frames. The diagrams of the angular capability of the ball joints, which are represented in angular coordinates, describe the form, orientation and size of the sockets from the spherical casings. Wears, shocks, functional locks or the compromising of the joint strength can occur if scarce sockets are implemented. The risk points, in which the angular parameters have maximum values, have been determined, the simulation being performed for a real system (vehicle). [ABSTRACT FROM AUTHOR]

This paper focuses on the mobility analysis of spatial and planar manipulators used in amusement parks. In this paper is presented a topological structure analysis for many types of serial and parallel manipulators, referring to the calculation of mobility (degree of freedom) of these types of complex mechanisms. It is used a new formula to calculate the mobility according to the number of drivelines, which are considered having identical operations. [ABSTRACT FROM AUTHOR]

Highlights: [•] Maintenance are critical for reducing costs of complex mechanical systems. [•] A risk based opportunistic maintenance model considering failure risk is proposed. [•] The global optimization algorithm is further developed to realize RBOM policy. [•] The influence of different parameters in the RBOM model is fully analyzed. [•] The developed methods can bring immediate benefits to the energy industry. [ABSTRACT FROM AUTHOR]

Several concepts of information theory (IT) are extended to cover the complex probability amplitudes (wave functions) of molecular quantum mechanics. The classical and non-classical aspects of the electronic structure are revealed by the electronic probability and phase distributions, respectively. The information terms due to the probability and current distributions are accounted for in the complementary Shannon and Fisher measures of the resultant information content of quantum states. Similar generalization of the information-distance descriptors is also established. The superposition principle (SP) of quantum mechanics, which introduces the conditional probabilities between quantum states, is used to generate a network of quantum communications in molecules, and to identify the non-additive contributions to physical and information quantities. The phase-relations in two-orbital model are explored. The orbital communication theory of the chemical bond introduces the entropic bond multiplicities and their partition into IT covalent/ionic components. The conditional probabilities between atomic orbitals, propagated via the network of the occupied molecular orbitals, which define the bond system and orbital communications in molecules, are generated from the bond-projected SP. In the one-determinantal representation of the molecular ground state the communication amplitudes are then related to elements of the charge and bond-order matrix. Molecular equilibria are reexamined and parallelism between the vertical (density-constrained) energy or entropy/information principles of IT and the corresponding thermodynamic criteria is emphasized. [ABSTRACT FROM AUTHOR]

Molecularrelaxation in antibacterial/antifungal agent: chloroxylenol(4-chloro-3,5-dimethylphenol, PCMX) in the solid state was studiedby the 1H NMR and quantum chemistry calculations. The temperaturedependencies of the proton spin–lattice relaxation time (T1) in the ranges 15–273 K (at 24.667MHz), 77–295 K (at 15 MHz), and 112–291 K at 90 MHzand the second moment (M2) of 1H NMR resonant line in the range 106–380 K were measured.The two minima in the temperature dependence of T1revealed two activation processes, whereas the M2dependence in the studied range was quiteflat and revealed the only significant reduction at 380 K. The lowtemperature part of T1(T) dependence indicated the occurrence of two processes characteristicof methyl bearing solids; the quantum mechanics governed incoherenttunneling (responsible for the low temperature flattening of T1) and the classical Arrhenius dependence governedhindered rotation (related to the wide low temperature minimum of0.066 s at 57 K, 24.667 MHz). The 2D potential energy surface obtainedusing DFT/B3LYP/6-311++G(2d,p) calculations revealed the inequivalenceof methyl groups and the lack of their interplay/coupling. The activationenergies of classical hindered rotation are 3.35 and 2.5 kJ/mol, whereastemperatures at which the proton tunneling Ttunfinally ceases are 52 and 63 K, for inequivalent methylgroups. Cp(T) required for the estimation of Ttunwas calculated purely theoretically on the basis of the Einsteinand Debye models of specific heat and 51 modes of atomic vibrations,4 internal rotations, and 3 torsions calculated by DFT. The −CH3motion (tunneling and classical) results in the reductionin the 1H NMR line second moment from 17.3 G2(rigid) to approximately 11.05 G2. The pointed high temperatureminimum T1(T) of 0.109s at 89 K, 24.667 MHz, which shifts with frequency, was assigned tosmall-angle libration jumps, by the Θ2= ±15°between two positions of equilibrium. The activation energy of thismotion estimated on the basis of the fit of the theoretical modelto the experimental points is 10.5 kJ/mol. The reduction in the 1H NMR line second moment assigned to this motion is much lower(due to order parameter s= 0.64) and equal to 1.6G2. The high temperature reduction from 9.6 G2to 0.9 G2at 380 K is a result of the phase transitionconnected with melting (385–389 K). [ABSTRACT FROM AUTHOR]

Physical simulation is a valuable tool in many fields of engineering for the tasks of design, prototyping, and testing. General-purpose operating systems (GPOS) are designed for real-fast tasks, such as offline simulation of complex physical models that should finish as soon as possible. Interfacing hardware at a given rate (as in a hardware-in-the-loop test) requires instead maximizing time determinism, for which real-time operating systems (RTOS) are designed. In this paper, real-fast and real-time performance of RTOS and GPOS are compared when simulating models of high complexity with large time steps. This type of applications is usually present in the automotive industry and requires a good trade-off between real-fast and real-time performance. The performance of an RTOS and a GPOS is compared by running a tire model scalable on the number of degrees-of-freedom and parallel threads. The benchmark shows that the GPOS present better performance in real-fast runs but worse in real-time due to nonexplicit task switches and to the latency associated with interprocess communication (IPC) and task switch. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we introduce a new technique, based on dual quaternions, for the analysis of closed linkages with revolute joints: the theory of bonds. The bond structure comprises a lot of information on closed revolute chains with a one-parametric mobility. We demonstrate the usefulness of bond theory by giving a new and transparent proof for the well-known classification of overconstrained 5R linkages. [Copyright &y& Elsevier]

This paper presents a geometrical and topological structure analysis for a spatial parallel manipulator (PMP), referring to the calculation of mobility (degree of freedom) of these types of complex mechanisms. In this paper it is used a new formula to calculate the mobility according to the number of drivelines, which are considered having identical operations. Also, in this paper it is used the bars method for the direct kinematics analysis of parallel manipulator with three actuators and after that it is analyzed an example solved by means of specialized software. [ABSTRACT FROM AUTHOR]

HMG-CoA reductase (HMGR) is the target of statins, cholesterol-lowering drugs prescribed to millions of patients worldwide. More recent research indicates that HMGR could be a useful target in the development of antimicrobial agents. Over the last seven decades, researchers have proposed a series of increasingly complex reaction mechanisms for this biomedically important enzyme. [ABSTRACT FROM AUTHOR]

Accurate fault prognosis is of vital importance for condition-based maintenance. As to complex mechanical systems, multiple sensors are often used to collect condition signals and the observation process may rather be non-Gaussian and non-stationary. Traditional hidden semi-Markov models cannot provide adequate representation for multivariate non-Gaussian and non-stationary time series. The innovation of this article is to extend classical hidden semi-Markov models by modeling the observation as a linear mixture of non-Gaussian multi-sensor signals. The proposed model is called as a multi-sensor mixtured hidden semi-Markov model. Under this new framework, modified parameter re-estimation algorithms are derived in detail based on the complete-data expectation maximization algorithm. In the end the proposed prognostic methodology is validated on a practical bearing application. The experimental results show that the proposed method is indeed promising to obtain better prognostic performance than classical hidden semi-Markov models. [ABSTRACT FROM AUTHOR]

We study entrainment in lock-release gravity currents using highly spatially resolved optical transmission experiments and quantitative analysis of the available potential energy of the flow. The principal results provide a resolution to the debate regarding the mechanism and degree of mixing in the head of a gravity current during the slumping phase. The nature of the complex internal mixing structure changes as a bore propagates from the tail to the head of the current during the slumping phase and overtakes its leading edge. We use quantitative methods to identify the connection between dynamics and entrainment and show that its manifestation as examined using different methodologies is the cause of previous contradictory experimental findings. Therefore, we conclude that the two main perspectives previously considered at odds are in accord. [ABSTRACT FROM AUTHOR]