Global Performance Index Research Articles

Enhancement of Corneal Visibility in Optical Coherence Tomography Images with Corneal Opacification.

PurposeTo establish and to rank the performance of a corneal adaptive compensation (CAC) algorithm in enhancing corneal images with scars acquired from three commercially available anterior segment optical coherence tomography (ASOCT) devices.MethodsHorizontal B-scans of the cornea were acquired from 10 patients using three ASOCT devices (Spectralis, RTVue, and Cirrus). We compared ASOCT image quality (with and without CAC) by computing the intralayer contrast (a measure of shadow removal), the interlayer contrast (a measure of tissue boundary visibility), and the tissue/background contrast (a measure of overall corneal visibility). All six groups (Spectralis, RTVue, Cirrus, Spectralis+CAC, RTVue+CAC, and Cirrus+CAC) were ranked according to a global performance index that averaged all contrast quantities.ResultsCAC provided mean intralayer contrasts improvement for all devices (all P < 0.05). Mean tissue/boundary contrasts were also improved for Spectralis and Cirrus (both P < 0.001). Mean interlayer contrasts were increased for Spectralis (P = 0.011) only. When comparing global performance indices, all CAC groups outperformed their corresponding baseline groups significantly. RTVue performed best without CAC, but Spectralis+CAC was ranked first.ConclusionsASOCT images of corneal scars may be enhanced by CAC through shadow removal, improved tissue boundary visibility, and enhanced corneal visibility against the image background. RTVue produces the finest baseline images but the best image quality can be achieved by applying CAC to Spectralis images.Translational RelevanceCAC could enhance visibility of corneal images with scars acquired from commercially available ASOCT devices and could aid preoperative planning of patients for ophthalmic procedures.

Optimal selection of the supporting points of large component aligned and positioned by parallel manipulator

Large components such as wing sections should be aligned and positioned in a desired position prior to the final manufacturing or assembly, so a digital alignment and position device based on six degree of freedom parallel manipulator with several prismatic-prismatic-prismatic-spherical branches was designed and fabricated to meet the needs. The digital alignment and position device is an alignment device based on the parallel manipulator, and it is also a positioning and holding fixture for large components manufacturing or assembly. In order to effectively and efficiently select the supporting points of large component where the digital alignment and position device branch is connected with, the performance of the parallel manipulator and the fixture should be comprehensively analyzed at the same time. The global performance indices such as the dexterity index, the bearing capacity index, and the stiffness index are calculated based on the mechanism Jacobean matrix of the parallel manipulator, and the positioning stability index is calculated based on the position Jacobean matrix of the fixture. The results show that the global performance indices are not related to the pose, but the positioning stability index is; in addition, all indices rely on the originally selected supporting points and provide the basis for the effective selection of the supporting points for large component aligned and positioned by the digital alignment and position device, which is based on parallel manipulator with prismatic- prismatic-prismatic-spherical pairs.

Kinematic design and optimization of a novel dual-orthogonal remote center-of-motion mechanism for craniotomy

Craniotomy is an essential neurosurgical procedure to remove a section of patient’s skull. In order to do this, the surgical tools need to execute a one-degree-of-freedom skull drilling followed by a two-degrees-of-freedom skull cutting. Particularly, this two-degrees-of-freedom skull cutting motion can be treated as a pivot rotation ideally. Therefore, the craniotomy tool motion is equivalent to a remote center-of-motion (RCM), which is renowned in surgical robotics. In this paper, we proposed a novel hybrid RCM mechanism for robotic craniotomy. The mechanism is made of two orthogonal parallelogram-based linkages, which make the two rotational degrees-of-freedom decoupled. We also studied the position and differential kinematics of this new architecture and analyzed its potential singular configurations. We then set the local and global kinematic performance indices for obtaining the optimal mechanism dimensions. Finally, according to the optimization result, we created a mechanical prototype to verify the motion of the designed mechanism.

Cost-Benefit Analysis for Energy Management in Public Buildings: Four Italian Case Studies

Improving energy efficiency in public buildings is one of the main challenges for a sustainable requalification of energy issues and a consequent reduction of greenhouse gas (GHG) emissions. This paper aims to provide preliminary information about economic costs and energy consumption reductions (benefits) of some considered interventions in existing public buildings. Methods include an analysis of some feasible interventions in four selected public buildings. Energy efficiency improvements have been assessed for each feasible intervention. The difference of the building global energy performance index (EPgl) has been assessed before and after each intervention. Economic costs of each intervention have been estimated by averaging the amount demanded by different companies for the same intervention. Results obtained show economic costs and the EPgl percentage improvement for each intervention, highlighting and allowing for the comparison of energy consumption reduction and relative economic costs. The research results come from data gathered from four public buildings, and as such they could not be used to generically identify cost-beneficial energy efficiency interventions for every context or building type. However, the data reveals useful cost based considerations for selecting energy efficiency interventions in other public buildings.

Cooperative guaranteed cost fault-tolerant control for multi-agent systems with time-varying actuator faults

This paper investigates the guaranteed cost consensus problem for multi-agent systems with actuator faults/uncertainties. For the leaderless case with actuator faults, a global performance index is constructed by all states and control inputs of all agents, where consensus regulation performances and control energy costs are considered simultaneously. Then, based on the relative state information of neighboring agents, a distributed cooperative guaranteed cost controller is designed, which not only makes the consensus problem solvable but also provides an upper bound of the given global performance index even in the presence of actuator faults. Extensions to the leader-following case with actuator faults and uncertainties are further studied. Finally, two simulation examples are provided to show the effectiveness of the proposed approach.

A modified replacement beam for analyzing building structures with damping systems

This paper assesses efficiency of the continuum method as the idealized system of building structures. A modified Coupled Two-Beam (CTB) model equipped with classical and non-classical damping has been proposed and solved analytically. In this system, complementary (non-classical) damping models composed of bending and shear mechanisms have been defined. A spatial shear damping model which is non-homogeneously distributed has been adopted in the CTB formulation and used to equivalently model passive dampers, viscous and viscoelastic devices, embedded in building systems. The application of continuum-based models for the dynamic analysis of shear wall systems has been further discussed. A reference example has been numerically analyzed to evaluate the efficiency of the presented CTB, and the optimization problems of the shear damping have been finally ascertained using local and global performance indices. The results reveal the superior performance of non-classical damping models against the classical damping. They show that the critical position of the first modal rotation in the CTB is reliable as the optimum placement of the shear damping. The results also prove the good efficiency of such a continuum model, in addition to its simplicity, for the fast estimation of dynamic responses and damping optimization issues in building systems.

Role of Three-Dimensional Speckle Tracking Echocardiography in the Quantification of Myocardial Iron Overload in Patients with Beta-Thalassemia Major.

The new three-dimensional speckle tracking echocardiography (3DSTE) may enable comprehensive quantification of global left ventricular (LV) myocardial mechanics. Twenty-four patients aged 29.3 ± 5.2 years and 22 controls were studied. 3DSTE was performed to assess LV 3D global strain, twist and torsion, ejection fraction, and systolic dyssynchrony index (SDI). The LV SDI was calculated as % of SD of times-to-peak strain of 16 segments/RR interval. The global performance index (GPI) was calculated as (global 3D strain·torsion)/SDI. Area under the receiver operating characteristic curve (AUC) was calculated to determine the capability of 3DSTE parameters to discriminate between patients with (cardiac magnetic resonance T2* <20 ms) and those without myocardial iron overload. Compared with controls, patients had significantly lower LV global 3D strain (P < 0.001), twist (P = 0.01), torsion (P = 0.04), and ejection fraction (P < 0.001) and greater SDI (P < 0.001). The GPI was lower in patients than controls (P < 0.001). T2* value correlated positively with global 3D strain (r = 0.74, P < 0.001) and GPI (r = 0.63, P = 0.001), and negatively with SDI (r = -0.44, P = 0.03). The AUCs of GPI, global 3D strain, ejection fraction, torsion, and 1/SDI were 0.94, 0.90, 0.87, 0.82, and 0.70, respectively. The GPI cutoff of 2.7°/cm had a sensitivity of 94.9% and a specificity of 88.9% of differentiating patients with from those without myocardial iron overload. The LV composite index of strain, torsion, and dyssynchrony derived from 3DSTE enables sensitive detection of myocardial iron overload in patients with thalassemia.

Carbon emissions dynamics, efficiency gains, and technological innovation in China's industrial sectors

In China, industrial sectors contribute carbon emissions at a larger scale and more rapidly growing pace than other end-use sectors. This paper thus aims to investigate the dynamic carbon emissions performance of China's industrial sectors using Malmquist-type index. Previous studies suffer from two limitations: the challenge of isolating carbon emissions performance from radial efficiency measures and the infeasibility problem in the calculation process. This paper proposes the non-radial global Malmquist carbon emissions performance index (NGMCPI) as a way of handling those two challenges with measuring dynamic changes in carbon emissions performance. The NGMCPI can be decomposed into efficiency change (EC) and technological change (TC) indexes, which represent the low-carbon catch-up and innovation effects, respectively. Based on the proposed indexes, we examine the dynamic changes in carbon emissions performance and its patterns for 38 Chinese industrial sectors over the 1990–2012 period. The results show that dynamic carbon emissions performance was mainly driven by the catch-up effect during the 1990s and boosted by innovation from 2000 to 2012. Some policy implications are proposed based on these empirical results.

Abstract 16408: Acute Changes in Tricuspid Annular Plane Systolic Excursion and Myocardial Deformation in Fetuses With Twin-twin Transfusion Syndrome After Selective Fetoscopic Laser Therapy

Introduction: Twin-twin transfusion syndrome (TTTS) is a serious complication affecting 10-15% of monochorionic twin gestations. Right ventricle (RV) function is often abnormal in these fetuses. Tricuspid annular plane systolic excursion (TAPSE) and myocardial strain are used as a marker of RV function in a number of disease processes postnatally. Hypothesis: Monitoring TAPSE and myocardial deformation may aid in assessing response to selective fetoscopic laser therapy (SFLP) in TTTS. Our objective was to determine whether TAPSE and myocardial deformation are altered after SFLP. Methods: Fetal echocardiograms of 22 recipient (RT) and donor (DT) twin pairs with TTTS were prospectively evaluated. TAPSE was obtained via M-mode through the lateral tricuspid annulus in the vertical 4-chamber (4C) view. 2D 4C views were acquired utilizing high frame rates (&gt;30 frames/sec) and were interrogated offline using feature-tracking software for strain analysis. Global RV longitudinal strain, TAPSE, and myocardial performance index (MPI) were compared pre and post-SFLP. Reproducibility of both TAPSE and RV strain was assessed. Results: Initial fetal echo was performed at 20.8 ± 2.3 weeks gestation. Median time between initial study and post-SFLP was 7 days (interquartile range 1 to 11 days). DT showed a slight improvement in strain, but not in TAPSE post-SFLP (Table). There was a significant, acute improvement both in global longitudinal strain and TAPSE among RT after SFLP (Table). Interobserver variability for TAPSE and strain was 4% vs 36%, respectively. Conclusion: After SFLP, there is an acute improvement in the global RV strain and TAPSE in RT, consistent with improved RV long-axis function or loading conditions. TAPSE is feasible in most fetuses, and is considerably more reproducible than myocardial strain. Further work examining the relationship between RV function and outcome post-SFLP is warranted in TTTS population.

Establishing the Power Factor Limitations for Synchronous Reluctance Machines

New variable-speed drives with improved-design synchronous reluctance machines may now be capable of reaching high efficiency, even up to the IE4 level [1]. These machines have been studied for many years and significant progress was made in the 1990s using axial laminations in the rotor [2]. At that time, the technology was reviewed and identified, in principle, as a viable alternative [3]. However, the axially-laminated rotor machine can be very difficult to manufacture and more recent designs use radial laminations with ducts. This paper brings further contributions by introducing new global performance indices and proposes a systematic optimization method for practical design. This establishes natural limitations of the machine when employing topologies that can be manufactured in high volumes and available high-performance materials.

Kinematics modeling and performance optimization of a kinematic-mechanics coupled continuum manipulator

An optimization design of a notched continuum manipulator is proposed in this paper, which is based on our defined performance evaluation indices. By experimental testing the mechanics-based forward kinematics and the curve-fitting-based inverse kinematics, our proposed kinematic-mechanics coupled continuum manipulator is equivalent to a robot that features discrete joints and rigid links. Based on the mechanics and the kinematics models, two kinematic performance evaluation indices are developed to comprehensively describe the performance distribution characteristics in the workspace. Firstly, the global stiffness performance index of the proposed manipulator is established based on the 3-dimensional 2-node Timoshenko beam element. Secondly, the equivalent Jacobian matrix, a linear mapping from the joint space to the task space of the continuum manipulator, is analyzed, and equivalent dexterity performance index is determined. Finally, the optimal design for our proposed continuum manipulator considering the stiffness performance and kinematics performance simultaneously is implemented as a case study utilizing the NAGA-II genetic algorithm. The results demonstrate that the optimized geometric parameters can improve the kinematic performance evaluation indices simultaneously, and our proposed kinematic performance evaluation indices can be applied and extended to the kinematic evaluation and the kinematic optimization of this kind of notched continuum manipulator.

Optimum design of a novel redundantly actuated parallel manipulator with multiple actuation modes for high kinematic and dynamic performance

A novel redundantly actuated parallel manipulator with multiple potential actuation modes is proposed in this paper to conquer the drawbacks of the traditional planar 5R parallel manipulator. Firstly, some feasible topology configurations are presented and then an optimum scheme was achieved through some selection criteria. Kinematic analysis indicates that the redundant actuation modes have remarkable advantage over the non-redundant actuation modes because the redundant actuation ones can completely conquer the type II singularities within the theoretical reachable workspace. To investigate the dynamics, the Lagrangian formulation is employed to establish the uniformly dynamic model of the proposed parallel manipulator with multiple actuation modes. Based upon the dynamic model, two global dynamic performance indices are proposed for minimization by taking into accounts both inertia and centrifugal/Coriolis effects. Finally, the dynamic dimensional synthesis is performed subject to geometric constraints and some kinematic performance constraints. By using this approach, the designer can obtain a set of optimum dimensional parameters satisfying both the kinematic and dynamic performance. This approach can be extended to the optimum design for other high-speed parallel manipulators, especially for the ones with multiple actuation modes.

Dimensional synthesis of a 3-DOF parallel manipulator with full circle rotation

Parallel robots are widely used in the academic and industrial fields. In spite of the numerous achievements in the design and dimensional synthesis of the low-mobility parallel robots, few research efforts are directed towards the asymmetric 3-DOF parallel robots whose end-effector can realize 2 translational and 1 rotational(2T1R) motion. In order to develop a manipulator with the capability of full circle rotation to enlarge the workspace, a new 2T1R parallel mechanism is proposed. The modeling approach and kinematic analysis of this proposed mechanism are investigated. Using the method of vector analysis, the inverse kinematic equations are established. This is followed by a vigorous proof that this mechanism attains an annular workspace through its circular rotation and 2 dimensional translations. Taking the first order perturbation of the kinematic equations, the error Jacobian matrix which represents the mapping relationship between the error sources of geometric parameters and the end-effector position errors is derived. With consideration of the constraint conditions of pressure angles and feasible workspace, the dimensional synthesis is conducted with a goal to minimize the global comprehensive performance index. The dimension parameters making the mechanism to have optimal error mapping and kinematic performance are obtained through the optimization algorithm. All these research achievements lay the foundation for the prototype building of such kind of parallel robots.

Kinetostatic analysis and design optimization of an n-finger underactuated hand exoskeleton

The concept of underactuation, applied to wearable exoskeletons to empower human users, is very promising, as it permits the designer to limit the number of actuators and consequently the bulk and weight of the device. This paper deals with a scheme of underactuated hand exoskeleton counting generically n fingers. The proposed architecture realizes such a principle at two stages: an intra-finger level and an inter-finger one. Both of them are here analyzed from a kinetostatic point of view; in particular, two alternative transmission mechanisms, relative to the inter-finger stage, are solved, in order to set a comparison. At this point, a design optimization can be performed: in fact, given an objective force profile on the finger phalanges, a number of geometric parameters can be investigated, to let the transmitted forces match the reference ones. Each configuration is numerically evaluated for what concerns the transmitted forces through a properly defined Global Performance Index, while the investigation is conducted through a stochastic algorithm. Finally, an example is provided: a 2-finger exoskeleton is presented and optimized, conceived to help astronauts during Extra Vehicular Activity, an operation that causes hand fatigue and therefore is an ideal field of application for empowering exoskeletons.

Designing Australia's energy future: applying global learnings to secure Australia's position as a leading global energy supplier

Low labour productivity, high costs, regulatory instability and remoteness of operations are some issues frequently raised by oil and gas operators and those considering investment in Australia. This extended abstract looks at the next wave of capital investment and presents recommendations on how to sustain Australia’s energy future. Australia has a significant opportunity to build future resilience and sustained growth through energy reform. This extended abstract draws heavily on the World Economic Forum's global energy architecture performance index (EAPI), developed in collaboration with Accenture, which ranks 125 countries globally on how well their energy system delivers economic growth and development, environmental sustainability and energy security and access. It is recommended that Australia should apply lessons from the global community and actively implement solutions to sustain the country's energy future. Using case studies from oil and gas regions around the world, recommendations are made to improve competitiveness and secure Australia’s position as a leading global energy supplier.

A Methodology to Link the Internal Heat Gains from Lighting to the Global Consumption for the Energy Certification of Buildings in Italy

This paper critically discusses the procedure prescribed by the Italian Technical Standards to account for the internal gains in the calculation of the energy performance indices for a building. This procedure is based on a tabular value set depending on the building usage only (e.g., 6 W/m2 for office buildings), independently of the site and of the controls for blinds and lighting systems. Instead, the paper proposes a new procedure, which relies on the lighting energy numerical indicator (LENI) according to the European Standard EN 15193:2007. Basically, the procedure consists of the following steps: 1) internal gains from lighting are calculated accounting for the integration between electric appliances and daylighting; 2) these gains are summed to the internal gains from occupants and appliances; 3) the global gains are used as input data to calculate the energy performance indices for an office building (for space heating, space cooling, and lighting consumption) following the Italian Technical Standards. The office building which was used as case-study is the Department of Energy of the Politecnico di Torino. This was assumed to be located both in Turin (northern Italy) and in Palermo (southern Italy). In the study, the use of a manual on/off switch and of a photodimming sensor was also compared. For each configuration, the single and the global energy performance indices were calculated comparing two approaches to calculate the internal gains (Italian standard vs. new proposed procedure): a shift of one energy class for the building energy label was observed depending on the approach, which was used

An Engineering Method for Comparing Selectively Compliant Joints in Robotic Structures

Large displacement compliant joints can substitute traditional kinematic pairs in robotic articulated structures for increasing ease-of-assembly, robustness, and safety. Nonetheless, besides their limited motion capabilities, compliant joints might be subjected to undesired spatial deformations which can deteriorate the system stability and performance whenever a low number of control inputs is available. In all these cases, it is convenient to select/design joint morphologies which enable a selectively compliant behavior, i.e., a low stiffness along a single desired direction. Within this context, this paper outlines an engineering method for quantifying the joint's selective compliance by means of local and global performance indices. The approach is validated by comparing two beam-like flexures whose analytic solution is known from the literature. Finally, two joint morphologies, previously employed in the fabrication of robotic/prosthetic hands, are critically compared on the basis of the proposed criteria.

Robust design of tuned mass dampers installed on multi-degree-of-freedom structures subjected to seismic action

This study deals with robust optimum design of tuned mass dampers installed on multi-degree-of-freedom systems subjected to stochastic seismic actions, assuming the structural and seismic model parameters to be uncertain. A new global performance index for evaluating the efficiency of protection systems is proposed, as an alternative to commonly used local performance indices such as the maximum interstorey drift. The latter can be considered a good estimator of seismic damage, but it does not measure the whole structural integrity. The direct perturbation method based on first order approximation is adopted to evaluate the effects of uncertainties on the response. The robust design is formulated as a multi-objective optimization problem, in which both the mean and the standard deviation of the performance index are simultaneously minimized. A comparison of the effectiveness and robustness of tuned mass dampers designed using local or global performance indices is carried out, considering different levels of uncertainty.

Dimensional synthesis and kinematics simulation of a high-speed plug seedling transplanting robot

To improve the automation and efficiency of plug seedlings transplanting in greenhouse, a high-speed plug seedling transplanting robot was designed by making use of a 2-DOF parallel translation mechanism with a pneumatic manipulator. According to the coordinates of healthy seedlings, the manipulator was driven by the mechanism to fetch and plant seedlings in a planned path. Based on the inverse kinematics of parallel mechanism, a global comprehensive performance index was proposed to synthesize a set of optimized dimension parameters for a good dynamic performance throughout the entire workspace. In accordance with the motion demand of transplanting robot, trajectory planning was carried out and quintic polynomial motion law was taken as the principle of operation for the manipulator. Based on the mechanism dimensions and assembly mode, a virtual prototype model was built, and kinematics simulation carried out. The simulation results were identical to the planed trajectory and a single transplanting cycle took 1.08s, verifying the rationality of the structure design and trajectory planning. Also, the kinematic parameters were obtained to provide a theoretical basis for optimization design and practical control of the physical prototype.

A balance of power principle for decentralized resource sharing

In a seminal 1978 paper Kleinrock (1979), Professor Leonard Kleinrock (“Kleinrock”) derived “rules of thumb” for flow-control, using a “power” metric of delay-throughput tradeoffs. This work stimulated a stream of, still on-going (e.g., Canzian et al., 2013), flow-control researches. A particularly challenging question, still widely open, has been: how can networks optimize a global performance index, such as power and through decentralized actions?At the same time, my Ph.D. thesis, under Len’s guidance, introduced microeconomic techniques for decentralized control of channel access schemes (Yemini and Kleinrock, 1979). This research too, continues to attract current interest (e.g., Chang et al., 2013).This paper introduces a generalized “power” metric for decentralized resource allocation, and uses it to derive novel Balance-of-Power principles, for Pareto optimal allocations. These principles substantially generalize and unify the results of Kleinrock (1979) and Yemini and Kleinrock (1979), as well as successor works, while shedding new light on resource sharing mechanisms in current virtual and cloud systems.