1,451 research outputs found

    Cable Robot Performance Evaluation by Wrench Exertion Capability

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    Although cable driven robots are a type of parallel manipulators, the evaluation of their performances cannot be carried out using the performance indices already developed for parallel robots with rigid links. This is an obvious consequence of the peculiar features of flexible cables-a cable can only exert a tensile and limited force in the direction of the cable itself. A comprehensive performance evaluation can certainly be attained by computing the maximum force (or torque) that can be exerted by the cables on the moving platform along a specific (or any) direction within the whole workspace. This is the idea behind the index-called the Wrench Exertion Capability (WEC)-which can be employed to evaluate the performance of any cable robot topology and is characterized by an efficient and simple formulation based on linear programming. By significantly improving a preliminary computation method for the WEC, this paper proposes an ultimate formulation suitable for any cable robot topology. Several numerical investigations on planar and spatial cable robots are presented to give evidence of the WEC usefulness, comparisons with popular performance indices are also provided

    Energy-Based Optimal Ranking of the Interior Modes for Reduced-Order Models under Periodic Excitation

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    This paper introduces a novel method for ranking and selecting the interior modes to be retained in the Craig-Bampton model reduction, in the case of linear vibrating systems under periodic excitation. The aim of the method is to provide an effective ranking of such modes and hence an optimal sequence according to which the interior modes should be progressively included to achieve a desired accuracy of the reduced-order model at the frequencies of interest, while keeping model dimensions to a minimum. An energy-based ranking (EBR) method is proposed, which exploits analytical coefficients to evaluate the contribution of each interior mode to the forced response of the full-order system. The application of the method to two representative systems is discussed: an ultrasonic horn and a vibratory feeder. The results show that the EBR method provides a very effective ranking of the most important interior modes and that it outperforms other state-of-the-art benchmark techniques

    Deformation Control in Rest-to-Rest Motion of Mechanisms with Flexible Links

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    This paper develops and validates experimentally a feedback strategy for the reduction of the link deformations in rest-to-rest motion of mechanisms with flexible links, named Delayed Reference Control (DRC). The technique takes advantage of the inertial coupling between rigid-bodymotion and elasticmotion to control the undesired link deformations by shifting in time the position reference through an action reference parameter. The action reference parameter is computed on the fly based on the sensed strains by solving analytically an optimization problem. An outer control loop is closed to compute the references for the position controllers of each actuator, which can be thought of as the inner control loop. The resulting multiloop architecture of the DRC is a relevant advantage over several traditional feedback controllers: DRC can be implemented by just adding an outer control loop to standard position controllers. A validation of the proposed control strategy is provided by applying the DRC to the real-time control of a four-bar linkage

    Multidimensional evaluation of performance: experimental application of the balanced scorecard in Ferrara university hospital

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    <p>Abstract</p> <p>Background and Aims</p> <p>One of the best-known performance planning and evaluation techniques utilising both monetary and non-monetary data is the <it>Balanced Scorecard (BSC)</it>. This is a means of rationalising the global activity of a business in the attempt to create value, and to translate the company vision into a set of tactical objectives and measurable strategies. The aim of this study was to implement and evaluate the use of BSC in two departments of the St. Anna University Hospital, Ferrara: the Analysis Laboratory and Digestive Endoscopy operating units (OU).</p> <p>Materials and methods</p> <p>With the collaboration of the health workers involved, a precise methodological programme was pursued: Definition of the strategic map from 4 perspectives, according to Kaplan and Norton, Definition of the Key Performance Areas (KPA), or macro-objectives, Identification of the cause-effect relationships between KPAs, Identification of the sub-objectives of each KPA, Definition of the Key Performance Indicators (KPI), Definition of the weight/importance of each objective in the global evaluation.</p> <p>Results</p> <p>The information gathered permitted the definition of macro- and sub-objectives for each perspective, as well as determining the relevant indicators, standards, weights, frequency of detection and means of acquisition. Strategic maps showing the cause/effect relationships in each OU were created, as were 'evaluation panels', which describe the global performance of each department. For each perspective, the fundamental data were summarised in one table. Evaluation of each perspective yielded a positive result for the majority of the objectives, and the global result (including all 4 perspectives) was found to be satisfactory.</p> <p>Discussion-Conclusion</p> <p>The Balanced Scorecard was implemented in the abovementioned OUs of St. Anna University Hospital, Ferrara, after the health workers themselves realised the need for change.</p> <p>In our research the employees were pleased to be evaluated, not only for the financial outcomes, but also for the satisfaction of improving internal procedure, relationships with the community and their own growth/learning. BSC is an ideal point of contact between the financial and clinical dimensions of management. However, difficulties in its application were faced, among these, at least in the initial phase, the lack of information systems able to drive it, and the complexity of the research for specific indicators needed to be overcome. The time factor (on average, at least two years are required) and the availability of technological resources were also limiting factors.</p> <p>The rapid diffusion of BSC among the principal international profit and non-profit organisations is testament to its great potential. This project could be seen as a preparatory phase in the strategical analysis of a subsequent business plan.</p

    The Effect of Anatomical Location of Lymph Node Metastases on Cancer Specific Survival in Patients with Clear Cell Renal Cell Carcinoma

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    Background: Positive nodal status (pN1) is an independent predictor of survival in renal cell carcinoma (RCC) patients. However, no study to date has tested whether the location of lymph node (LN) metastases does affect oncologic outcomes in a population submitted to radical nephrectomy (RN) and extended lymph node dissection (eLND). Objective: To describe nodal disease dissemination in clear cell RCC (ccRCC) patients and to assess the effect of the anatomical sites and the number of nodal areas affected on cancer specific mortality (CSM). Design, setting and partecipants: The study included 415 patients who underwent RN and eLND, defined as the removal of hilar, side-specific (pre/paraaortic or pre/paracaval) and interaortocaval LNs for ccRCC, at two institutions. Outcome measurement and statistical analysis: Descriptive statistics were used to depict nodal dissemination in pN1 patients, stratified according to nodal site and number of involved areas. Multivariable Cox regression analyses and Kaplan-Meier curves were used to explore the relationship between pN1 disease features and survival outcomes. Results and limitations: Median number of removed LN was 14 (IQR 9\u201319); 23% of patients were pN1. Among patients with one involved nodal site, 54 and 26% of patients were positive only in side-specific and interaortocaval station, respectively. The most frequent nodal site was the interaortocaval and side-specific one, for right and left ccRCC, respectively. Interaortocaval nodal positivity (HR 2.3, CI 95%: 1.3\u20133.9, p &lt; 0.01) represented an independent predictor of CSM. Conclusions: When ccRCC patient harbour nodal disease, its spreading can occur at any nodal station without involving the others. The presence of interoartocaval positive nodes does affect oncologic outcomes. Patient summary: Lymph node invasion in patients with clear cell renal cell carcinoma is not following a fixed anatomical pattern. An extended lymph node dissection, during treatment for primary kidney tumour, would aid patient risk stratification and multimodality upfront treatment

    Development and Validation of a New Prognostic System for Patients with Hepatocellular Carcinoma

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    BACKGROUND: Prognostic assessment in patients with hepatocellular carcinoma (HCC) remains controversial. Using the Italian Liver Cancer (ITA.LI.CA) database as a training set, we sought to develop and validate a new prognostic system for patients with HCC. METHODS AND FINDINGS: Prospective collected databases from Italy (training cohort, n = 3,628; internal validation cohort, n = 1,555) and Taiwan (external validation cohort, n = 2,651) were used to develop the ITA.LI.CA prognostic system. We first defined ITA.LI.CA stages (0, A, B1, B2, B3, C) using only tumor characteristics (largest tumor diameter, number of nodules, intra- and extrahepatic macroscopic vascular invasion, extrahepatic metastases). A parametric multivariable survival model was then used to calculate the relative prognostic value of ITA.LI.CA tumor stage, Eastern Cooperative Oncology Group (ECOG) performance status, Child-Pugh score (CPS), and alpha-fetoprotein (AFP) in predicting individual survival. Based on the model results, an ITA.LI.CA integrated prognostic score (from 0 to 13 points) was constructed, and its prognostic power compared with that of other integrated systems (BCLC, HKLC, MESIAH, CLIP, JIS). Median follow-up was 58 mo for Italian patients (interquartile range, 26-106 mo) and 39 mo for Taiwanese patients (interquartile range, 12-61 mo). The ITA.LI.CA integrated prognostic score showed optimal discrimination and calibration abilities in Italian patients. Observed median survival in the training and internal validation sets was 57 and 61 mo, respectively, in quartile 1 (ITA.LI.CA score 64 1), 43 and 38 mo in quartile 2 (ITA.LI.CA score 2-3), 23 and 23 mo in quartile 3 (ITA.LI.CA score 4-5), and 9 and 8 mo in quartile 4 (ITA.LI.CA score &gt; 5). Observed and predicted median survival in the training and internal validation sets largely coincided. Although observed and predicted survival estimations were significantly lower (log-rank test, p &lt; 0.001) in Italian than in Taiwanese patients, the ITA.LI.CA score maintained very high discrimination and calibration features also in the external validation cohort. The concordance index (C index) of the ITA.LI.CA score in the internal and external validation cohorts was 0.71 and 0.78, respectively. The ITA.LI.CA score's prognostic ability was significantly better (p &lt; 0.001) than that of BCLC stage (respective C indexes of 0.64 and 0.73), CLIP score (0.68 and 0.75), JIS stage (0.67 and 0.70), MESIAH score (0.69 and 0.77), and HKLC stage (0.68 and 0.75). The main limitations of this study are its retrospective nature and the intrinsically significant differences between the Taiwanese and Italian groups. CONCLUSIONS: The ITA.LI.CA prognostic system includes both a tumor staging-stratifying patients with HCC into six main stages (0, A, B1, B2, B3, and C)-and a prognostic score-integrating ITA.LI.CA tumor staging, CPS, ECOG performance status, and AFP. The ITA.LI.CA prognostic system shows a strong ability to predict individual survival in European and Asian populations

    Plasma cholesterol and lipoprotein levels in relation to tumor aggressiveness and survival in HCC patients

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    open13Hepatocellular carcinoma is associated with several chronic liver diseases, especially chronic hepatitis B virus, hepatitis C virus, and alcoholism. It is increasingly appreciated that obesity/metabolic syndrome is also associated with chronic liver disease and subsequent hepatocellular carcinoma.openCarr, Brian I; Giannelli, Gianluigi; Guerra, Vito; Giannini, Edoardo G; Farinati, Fabio; Rapaccini, Gian Ludovico; Marco, Maria Di; Zoli, Marco; Caturelli, Eugenio; Masotto, Alberto; Virdone, Roberto; Sacco, Rodolfo; Trevisani, FrancoCarr, Brian I; Giannelli, Gianluigi; Guerra, Vito; Giannini, Edoardo G; Farinati, Fabio; Rapaccini, Gian Ludovico; Marco, Maria Di; Zoli, Marco; Caturelli, Eugenio; Masotto, Alberto; Virdone, Roberto; Sacco, Rodolfo; Trevisani, Franc

    A Liver Index and its Relationship to Indices of HCC Aggressiveness

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    A Hepatocellular (HCC) Aggressiveness Index was recently constructed, consisting of the sum of the scores for the 4 clinical parameters of maximum tumor size, multifocality, presence of portal vein thrombus and blood alphafetoprotein levels. It was observed that there was an association with several liver function tests. We have now formed a Liver Index from the 4 liver parameters with the highest hazard ratios with respect to HCC aggressiveness, namely: blood total bilirubin, gamma glutamyl transpeptidase (GGTP), albumin and platelet levels (cirrhosis surrogate). We found that the scores for the Liver Index related significantly to survival, but also to the Aggressiveness Index and to its individual HCC components as well as showing significant trends with the components. These results support the hypothesis that liver function is not only an important prognostic factor in HCC patients, but may also be involved in HCC biology and aggressiveness. Blood albumin, GGTP, albumin and platelet levels were used to create a Liver Index that related significantly to parameters of HCC aggressiveness
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