A chaotic bio-mechanics model of dairy cow leg

The purpose of this chapter is to develop project system dynamic (SD) models that mirror non-linear Monte Carlo N-SCRA models of project Zemblanity. Only schedule part of risk exposure is considered. Required recalculations of parameters is undertaken. As these are no one-to-one relations between the parameters of the SD and Monte Carlo models, required assumptions are applied. These can be used for mutual calibrations of the two types of models. Two SD models are built that reflect on the project risk exposure before and after risk interaction addressing. Limitations of the project SD modelling are revealed. The SD modelling results demonstrate a good alignment of corresponding non-linear schedule and cost risk analysis (N-SCRA) and SD models. One additional SD model is built to explicitly demonstrate a contribution of risk compounding to overall project duration. The three workable SD models are available on the book’s companion website.

A CCURATEmodeling of the differential translation and rotation between two spacecraft is essential for cooperative distributed space systems, spacecraft formation flying (SFF), rendezvous, and docking. High-fidelity relative motion modeling, as opposed to absolute motion modeling, is particularly important for autonomous missions [1]. Point-mass models for relative spacecraft translational motion have been extensively studied over the past 50 years, since Clohessy and Wiltshire (CW) presented a rendezvous model for a circular reference orbit and a spherical Earth [2]. Following the work of Clohessy and Wiltshire, variants on the point-mass model were developed, such as generalizations to elliptic reference orbits [3–5] and an oblate Earth [6,7]. The growing interest in SFF motivated the research of relative spacecraft motion modeling, yielding more accurate and complete equations and solutions for perturbed relative motion [8–10]. However, most of the works focused on point-mass, 3 degrees-offreedom (DOF) spacecraft. Obviously, performing a space mission that consists of several cooperative space vehicles requires modeling the relative rotational motion in addition to the relative translation, that is, 6-DOF models. Models for the relative motion of 6-DOF spacecraft have gained attention in the literature only in recent years. Among the first to suggest treating the spacecraft relative angular velocity in an SFF control problem were Pan and Kapila [11], who addressed the coupled translational and rotational dynamics of two spacecraft. By defining two body-fixed reference frames, one attached to the leader and the other attached to the follower, it was proposed [11] to use a two-part relative motion model: one that accounts for the relative translational dynamics of the body-fixed coordinate frame origins, and another that captures the relative attitude dynamics of the two body-fixed frames. A similar modeling approach was used for relative motion estimation [1]. In addition, tensorial equations of motion for a formation consisting ofN spacecraft, each modeled as a rigid body, were derived [12]. However, only the absolute equations of motion were developed [12]; a relative version of these equations was not given. Moreover, a clear mathematical relationship between the developed models and the traditional nonlinear point-mass relative motion and CW models was not provided. The coupling between the translational and rotational motion in the aforementioned models [1,11] was induced by gravity torques. The kinematic coupling, which is essentially a projection of the rotational motion about the center of mass (c.m.) onto the relative translational configuration space, was neglected. It is this kinematic coupling that the current paper is concerned with. In general, rigid-body dynamics can be represented as translation of the c.m. and rotation about the c.m. [13]. Thus, spacecraft relative motion must be composed by combining the relative translational and rotational dynamics of arbitrary points on the spacecraft. Whenever one of these points does not coincide with the spacecraft’s c.m., a kinematic coupling between the rotational and translational dynamics of these points is obtained. The purpose of this paper is to quantify the kinematic coupling effect and to show that this effect is key for high-precision modeling of tight SFF, rendezvous, and docking. This effect is also important in vision-based relative attitude and position control, where arbitrary feature points on a target vehicle are to be tracked. Given two rigidbody spacecraft, the model presented herein is formulated in a general manner that describes the motion between any two arbitrary points on the spacecraft. The relative translational motion is then generated by both the spacecraft orbitalmotion and the rotation about the c.m. In addition, this paper provides a CW-like approximation of the relative motion that includes the kinematic coupling. This new approximation is aimed at alleviating an apparent contradiction in linearized relative motion theories: to obtain linear equations of motion, the spacecraft are assumed to operate in close proximity. However, if the spacecraft are close to each other, then they can no longer be treated as point masses, because the spacecraft shape and size affects the relative translation between off-c.m. points. This effect is accentuated as the distances between spacecraft decrease. The remainder of this paper is organized as follows. First, a background on the relative position and attitude dynamics is given. Then, a new coupled relative spacecraft motion model is presented. The newly developed model is then examined in a simulation.

We develop a high order, multi-loop nonlinear (system dynamics) model for socio-economic sustainability assessment of groundwater resources. Structure and behavior validation of dynamic system models as such pose several challenges. While some of these challenges stem from the ambiguities in theoretical representations of multi-sectorial systems, others stem from the lack of sufficient time varying data sets to calibrate the model reference behavior. In this paper, we focus on partial validation of the groundwater component of this multi-sectorial model. For this purpose, we test the behavioral response of the system dynamics model against a process-based surface/subsurface hydrogeological model. For testing purposes, the hydrogeological model is regarded as the best representation of the reality (a synthetic reality), concerning groundwater flows and accumulations. The system dynamics model is built on Stella Architect and runs on annual time steps for a time horizon of 20 years. The embedded groundwater is a non-spatial, one compartment representation -a box model- of the saturated zone, changing with lateral flows, vertical recharge and anthropogenic extractions. The hydrogeological model is built on the UFZ1-MODFLOW computer program. It simulates evapotranspiration and one-dimensional vertical flow through the vadose zone, and horizontal flow through the underlying aquifer system. The model was developed based on available borehole and pumping tests data and calibrated using observed transient groundwater level data. While the box model and the hydrogeological model are different structural entities, the spatially aggregated behavioral response of the latter under specific experimental conditions help structural validation and calibration of the box model. For this purpose, we apply multiple tests on the lateral and vertical recharge of the hydrogeological model under constant boundary hydraulic head, precipitation, irrigation and evapotranspiration conditions to observe the response in spatially aggregated hydraulic head. We repeat the same experiments on the box model, first to confirm the equations used to simulate the aggregated hydraulic flows, and to estimate the two parameters, “aquifer bottom” and “fractional evaporation” for calibration of the spatially aggregated hydraulic head. The testing process is very useful to arrive at a reliable water budget and hydraulic head response in the system dynamics model, which is going to serve for socio-economic sustainability analysis under stakeholder participation.This work was developed under the scope of the InTheMED project. InTheMED is part of the PRIMA program supported by the European Union’s HORIZON 2020 research and innovation program under grant agreement No 1923.

Objective To explore the clinical characteristics and outcome of correction with Ilizarov fixator for the knee deformities.Methods From May 2003 to April 2010,21 patients (22 knees) underwent knee deformity correction with Ilizarov fixator,including 12 males and 9 females with an average age of 20.3 years (range,8-48).Causes of the deformities included poliomyelitis in 4,burn in 2,osteomyelitis in 2,trauma in 9,Blount diseases in 2,and multiple osteochondromatosis in 2.Five patients had fixed flexion contracture due to soft tissue,they were corrected through a combination of Ilizarov's frame crossover the joint with a pair of hinges by gradual posterior distraction.Eight patients (9 limbs) had one way bony deformities and 7 patients had complex deformations.The frame with 4 hinge-posts was used for correction by restoring the alignment firstly,and then gradual lengthening to correct bone shortening.Additionally,an overlay frame of the above mentioned combinations was applied for correction of bony deformity combined with soft tissue contracture for 1 patient.Results The average time in frame was 22.3 weeks (range,12-36).At the time of removing frame,satisfactory alignment was achieved in all of the affected knees,and solid bony healing was obtained in osteotomy or bone lengthening area in 16 patients (17 limbs) with bony correction.All patients were followed up for an average of 32.1 months (range,6-86).The range of motion was improved from 102.14°±49.36° preoperatively to 126.90°±24.31° at the final follow-up.Additionally,the Japanese Orthopaedic Association knee score was also increased from 50.24±23.64 before operation to 85.71±10.52 at the final follow-up.All of them were able to walk without crutches,deal with daily life independently.Only 2 patients with the range of motion of the knee less than 90° were not able to squat.Conclusion Ilizarov fixator has advantages of minimal intervention to local tissue in operation and nimble adjustment at any time,and disadvantages related to a longer time in frame. Key words: Knee joint; Abnormalities; Ilizarov technique

Geographic Information System (GIS) is an information technology that is readily applied as a decision aid for a variety of water resource applications. System dynamics as a method of computer simulation of dynamic systems is based on the basic concept of stock with incoming and outgoing flows. In most real-world problems the change in the level of the basin is considered to be the result of summation of incoming and outgoing flows over a certain period of time, taking into account the initial level of the basin. This makes system dynamics an appropriate tool for modelling the behaviour of water basins. A digital terrain model consists of a digital elevation model and a digital model of the situation. For the needs of system dynamics modelling in this case-study only the digital elevation model (DEM) is used. GIS product - DEM -usage in system dynamics models advances simulation-based analysis and decision making for local and regional operational forecasting. The task of the article is to formulate both necessary and sufficient requirements for DEM usage in effective forecasting of water basin behaviour with system dynamics model. Within the proposed approach simple system dynamics models of a basin are developed and verified. These models include incoming and outgoing flow models in form of time-series and basin level DEMbased model. The incoming flow is defined with a hydrograph. The water regime of the basin is determined by its geometrical properties. The outgoing flow is formed at the exit from the basin. The models are formalized as a set of first-order difference equations, which are solved sequentially after constant time steps. The solutions provide simulation progress over time. The concept of constant time step is associated with the periodicity of observations of the natural water objects. The basin level function of the volume makes it possible to develop the system dynamics model of the basin suitable for simulation of the level changes in the basin. The developed system dynamics models are used for experimentation with various scenarios of the behaviour of the system under investigation and for forecasting the consequences of changes in parameters or structure of the system. The requirements for DEM usage in system dynamics models are formulated. The application of system dynamics with incorporated DEMbased basin models makes it possible to analyse the behaviour of the investigated basins and to obtain operational forecasts of the situation for various scenarios. Further research is outlined on the accuracy of simulation results depending on the complexity increase in the simulated object for closer similarity to real reservoirs.

<div class="htmlview paragraph">A finite element (FE) model that can predict impact response and injuries to a human pelvis and lower limb was developed in PAM-CRASH™ by accurately representing human anatomical structures.</div> <div class="htmlview paragraph">In our previous study, three-dimensional (3D) geometry of the thigh, leg and knee joint was developed based on MRI scans from a human volunteer. 3D geometry of a bony pelvis created in this study was based on CT scans from a Post Mortem Human Subject (PMHS).</div> <div class="htmlview paragraph">The model was validated using published quasi-static and dynamic test results with human pelves and lower limbs. The thigh and leg models were validated against recently published dynamic 3-point bending test results with off-center loading. The validation results showed that this model can reproduce force-deflection and moment-deflection responses of a human thigh and leg in various loading conditions along with average force and moment at fracture. In terms of the ligaments in the knee joint, newly published high rate tensile test results were used for comparison of force-deflection response in order to confirm validity of the strain rate dependency specified in the material models for the ligaments. The knee joint model was validated against dynamic valgus bending tests. The results indicated that the model can reproduce bending moment-bending angle response of the human knee along with average bending moment and bending angle at ligament failure. The pelvis model was validated against published results of quasi-static lateral compressive and tensile tests as well as dynamic compressive tests. It was confirmed that the model can simulate quasi-static and dynamic force-deflection responses of human pelves along with average force and deflection at fracture.</div> <div class="htmlview paragraph">Those validations showed that the model developed in this study can cover various loading conditions to a pedestrian lower limb while simulating lateral impact responses of a pedestrian pelvis.</div>

CAD systems today are feature-based in that they represent geometry via a collection of features, and associated feature parameters. During the design process, feature parameters are optimized to meet various design objectives including functionality, manufacturability, aesthetics, etc. This paper focuses on predicting the impact of parametric feature changes on quantities of interest, such as average stress within a given region, etc. When the parametric change is sufficiently small, one can rely on classic shape sensitivity and reanalysis methods to rapidly predict the desired quantity of interest. However, when the parametric changes are large, both methods are unreliable.In this paper, we propose an alternate methodology for predicting the impact of large parametric feature changes on field problems, and thereby opening fundamentally new avenues for design exploration and parametric optimization. The proposed methodology is based on the novel concept of feature sensitivity, a generalization of topological sensitivity. Topological sensitivity captures the first-order change in quantities of interest when a small spherical hole is created within an existing geometry. This is generalized here to an arbitrary collection of internal or boundary features. Subsequently, we demonstrate its application to large parametric feature changes. The methodology is illustrated via numerical experiments involving a 2-D scalar field problem.

This paper presents a method and algorithms for automatic modeling of anatomical joint motion. The method relies on collision detection to achieve stable positions and orientations of the knee joint by evaluating the relative motion of the tibia with respect to the femur (for example, flexion-extension). The stable positions then become the basis for a look-up table employed in the animation of the joint. The strength of this method lies in its robustness to animate any normal anatomical joint. It is also expandable to other anatomical joints given a set of kinematic constraints for the joint type as well as a high-resolution, static, 3-D model of the joint. The demonstration could be patient specific if a person's real anatomical data could be obtained from a medical imaging modality such as computed tomography or magnetic resonance imaging. Otherwise, the demonstration requires the scaling of a generic joint based on patient characteristics. Compared with current teaching strategies, this Virtual Reality Dynamic Anatomy (VRDA) tool aims to greatly enhance students' understanding of 3-D human anatomy and joint motions. A preliminary demonstration of the optical superimposition of a generic knee joint on a leg model is shown.

We address artisanal and small-scale gold mining in Peru. Using the data collected through field visits, we develop a System Dynamics (SD) model to examine the current operations of the gold supply chain, and its interplay with mercury and gas suppliers. The current mining operations cause potential health and environmental issues, due to high mercury usage, and other issues (e.g., safety issues). As a potential solution to overcome such problems, we consider incorporating a cyanide processing facility into the SD model, where we examine the amount of ore that a miner would be willing to sell to the facility under several payback scenarios. We formulate a mixed-integer programming model that prescribes the optimal transition plan of a miner from local production to selling their ore to the facility within a time horizon that maximizes a miner’s profit. The optimal solution provides a 22% improvement in the miners’ profit over that of their current operations. We also conduct a sensitivity analysis to test the sensitivity of the optimal solution to the changes in several input parameters. We discuss that the solution is most sensitive to the gold price changes and the least sensitive to the local production cost changes.

Animal joint motion is a combination of rotation and translational motion, which brings high stability, high energy utilization, and other advantages. At present, the hinge joint is widely used in the legged robot. The simple motion characteristic of the hinge joint rotating around the fixed axis limits the improvement of the robot's motion performance. In this paper, by imitating the knee joint of a kangaroo, we propose a new bionic geared five-bar knee joint mechanism to improve the energy utilization rate of the legged robot and reduce the required driving power. Firstly, based on image processing technology, the trajectory curve of the instantaneous center of rotation (ICR) of the kangaroo knee joint was quickly obtained. Then, the bionic knee joint was designed by the single-degree-of-freedom geared five-bar mechanism and the parameters for each part of the mechanism were optimized. Finally, based on the inverted pendulum model and the Newton-Euler recursive method, the dynamics model of the single leg of the robot in the landing stage was established, and the influence of the designed bionic knee joint and hinge joint on the robot's motion performance was compared and analyzed. The proposed bionic geared five-bar knee joint mechanism can more closely track the given trajectory of the total center of mass motion, has abundant motion characteristics, and can effectively reduce the power demand and energy consumption of the robot knee actuators under the high-speed running and jumping gait.

Nonlinear model order reduction and vibration control of a membrane antenna structure

Review of modelling energy transitions pathways with application to energy system flexibility

Adaptive Control of a Flexible Structure

ADAPTIVE CONTROL OF A FLEXIBLE STRUCTURE

System Dynamics is methodology that requires building the integrated system dynamics models using computer simulation to gain the insight of the social, economic, and business problems and keep on experimenting with the model to propose the alternative solutions to make the system better behaved. This paper attempts to describes the business models form simple to complex using system dynamics modeling while identifying the different facets of factory dynamics. Single stock Banana Shop to Multi-stock Complex Model Labour Intensive 3PL Logistics firm share the modelling steps and keep on adding the factory structures to make the business complex gradually. Each model helps to explore the different mode of behaviours. Production, inventory, workforce, information systems, shipments and customer orders are the dynamic variables which change over the period of time and all are interacting in the multi-stock complex 3PL logistic firm model. Model structures and interactions among of different variables not only give the model understanding but also reveal the policies to make the system better behaved. Feedback notion is other significant property for system dynamics models. Using the factory information, its dynamics is modelled step by step and its behavior is analyzed at each stage to gain the real-life wisdom. As we keep on adding the stocks and rates to improve the model of factory dynamics, each step highlights the model insight and understanding. Model validation is done after building the model while using different tests. Plausible policies are suggested on the basis of parametric changes and structural changes of the model that set the guidelines for policy formulation. This model development process indicates how a Systems Dynamics model addresses the corporate issues and designs the firm of its own choice.