Proof of Principle of an On-Line Digitizer with +18 ppm Repeatability and 1.2 μs Real-Time Delay for Power Converters Control Loop

The proof of principle of an on-line digitizer designed to be integrated into the digital control loop of a high-voltage modulator for ultra-repeatable power converters is presented. The presented selective analogue zoom allows digitizing with 18 ppm repeatability the voltage around the nominal level (10V1 V) and, at the same time, the initial transients with relaxed performance. In addition, in order not to jeopardize the digital control loop stability, the whole digitizing system has to introduce a low real-time delay; this is assessed to be less than 1:2 s. Initially, the specifications of the real-time control are presented and translated into data acquisition requirements. Then, the main design choices of the digitizer are discussed and Pspice simulation results are reported to validate the concept design. Finally, experimental results of a validation case study developed for the power converter designed at ETH Zurich and University of Laval for the new linear particle accelerator under study at CERN, the Compact LInear Collider CLIC, are reported and compared with the simulation outcomes

LoCuSS: Hydrostatic Mass Measurements of the High-LXL_X Cluster Sample -- Cross-calibration of Chandra and XMM-Newton

We present a consistent analysis of Chandra and XMM-Newton observations of an approximately mass-selected sample of 50 galaxy clusters at $0.15<z<0.3$ -- the "LoCuSS High-$L_X$ Sample". We apply the same analysis methods to data from both satellites, including newly developed analytic background models that predict the spatial variation of the Chandra and XMM-Newton backgrounds to $<2\%$ and $<5\%$ precision respectively. To verify the cross-calibration of Chandra and XMM-Newton-based cluster mass measurements, we derive the mass profiles of the 21 clusters that have been observed with both satellites, extracting surface brightness and temperature profiles from identical regions of the respective datasets. We obtain consistent results for the gas and total hydrostatic cluster masses: the average ratio of Chandra- to XMM-Newton-based measurements of $M_{\rm gas}$ and $M_X$ at $r_{500}$ are $0.99\pm0.02$ and $1.02\pm0.05$, respectively with an intrinsic scatter of $\sim3\%$ for gas masses and $\sim8\%$ for hydrostatic masses. Comparison of our hydrostatic mass measurements at $r_{500}$ with the latest LoCuSS weak-lensing results indicate that the data are consistent with non-thermal pressure support at this radius of $\sim7\%$. We also investigate the scaling relation between our hydrostatic cluster masses and published integrated Compton parameter $Y_{sph}$ measurements from the Sunyaev-Zel'dovich Array. We measure a scatter in mass at fixed $Y_{sph}$ of $\sim16\%$ at $\Delta=500$, which is consistent with theoretical predictions of $\sim10-15\%$ scatter.Comment: 21 pages, 11 figure

Polynomial Approach for Filtering and Identification of a Class of Uncertain Systems

Abstract this paper considers the filtering and identification problems for a class of discrete-time uncertain stochastic systems that admit a finite number of linear working modes. It is shown here that this class of uncertain systems can be modeled by using a suitably defined extended system, whose state evolves according to a bilinear model. A polynomial filtering algorithm is derived for such extended system, which readily provides the polynomial estimates of both the original state and the working mode. Simulations show the effectiveness of the proposed approach and the improvements with respect to standard linear filtering algorithms

Incidentally detection of non-palpable testicular nodules at scrotal ultrasound: What is new?

The increased use of ultrasound in patients with urological and andrological symptoms has given an higher detection of intra-testicular nodules. Most of these lesions are hypoechoic and their interpretation is often equivocal. Recently, new ultrasound techniques have been developed alongside of B-mode and color-Doppler ultrasound. Although not completely standardized, contrast-enhanced ultrasound (CEUS) and tissue elastography (TE), added to traditional ultrasonography, can provide useful information about the correct interpretation of incidentally detected non-palpable testicular nodules. The purpose of this review article is to illustrate these new techniques in the patient management

Role of Cable Forces in the Model Updating of Cable-Stayed Bridges

This paper presents and discusses the feasibility of complete model updating of cable-stayed bridges using experimental estimates of the cable forces and modal parameters. The procedure is applied to the model updating of a curved cable-stayed bridge in Venice (Italy). Conventional optimization problems of mass and stiffness using ambient vibration data are prone to ill-posedness and ill-conditioning. Generally, the scholar must assume one of the two to achieve a trustworthy optimization. This paper demonstrates that it is possible to assess a large set of parameters affecting the mass and stiffness of a cable-stayed bridge following a step-wise procedure based on ambient vibration tests. Preliminary variance-based sensitivity analysis supports the reduction in the number of parameters to be calibrated. Then, the selected parameters are tuned using a meta-heuristic optimization algorithm. In the considered case study, the sensitivity analyses highlight the significance of the following: the concrete mass, the vertical stiffness of the bearings, and the concrete Young's modulus of the deck and the tower. However, optimizing all the unknowns using a single objective function does not lead to optima within the search domain. Therefore, the authors show that a three-step optimization is required in the considered case study to achieve convergence within the parameters' space. As a result, all the twelve modes of the calibrated model perfectly match the experimental ones, with the modal assurance criterion (MAC) higher than 0.9. In addition, the cable forces of the calibrated model present a good match with the experimental ones, with an average percentage error equal to 11%

A generalised multi-attribute task sequencing approach for robotics optical inspection systems

Robot programming usually consists of four steps: (1) task planning; (2) task sequencing; (3) path planning and (4) motion planning. Task (2) and (3–4) are strongly coupled. For example, the optimal robot path, which is function of the robot kinematics, relies on the pre-defined schedule of tasks, whose sequencing is computed based on the assumption that the travelling “cost” from one task to the next is only driven by the Euclidean distance in Cartesian space. Current methods tends to decouple the problem and sequentially compute the task sequencing in the T-space, and then compute the robot path by solving the inverse kinematics in the C-space. However, those approaches suffer the capability to reach a global optimum. This paper aims at developing a novel approach which integrates some of the key computational requirements of the path planning in the early stage of the task sequencing. Multi-attribute objectives are introduced to take into account: robot pose and reachability, data quality, obstacles avoidance, overall cycle time. The paper introduces a novel multi-attribute approach to find the optimized task sequencing via candidate poses solving inverse kinematics in the T-space. This is based on the core idea to combine T-space and C-space. The proposed solution has been tested on a vision-based inspection robot system with application to automotive body assembly systems. Results could however impact a wider area, from navigation systems, game and graph theory, to autonomous driving systems

DISTRIBUTED-DELAY MODELS OF THE GLUCOSE-INSULIN HOMEOSTASIS AND ASYMPTOTIC STATE OBSERVATION

Abstract In this paper the problem of the real-time reconstruction of plasma insulin concentration by using only blood glucose measurements is investigated. This is an interesting problem because the knowledge of the time course of the glucose and insulin concentrations in an individual provides precious informations concerning its health state, and may assume the role of a clinical instrument. For the purpose of the reconstruction of the insulinemia a dynamical model of the glucose-insuline homeostasis is required. The present work considers distributed delay models. Such models have been preferred in recent papers with respect to the standard Minimal Models, available in literature from 70's, because they allow to couple the glucose and insulin dynamics in a unique extended system, whose solutions have been proven to be positive, bounded, and globally asymptotically stable around the basal values of the equilibrium point. Data are acquired according to the Intra Venous Glucose Tolerance Test (IVGTT). Simulation results are reported in order to validate the developed theory

Potential Applications of Three-Dimensional Printing in the Hospital Network: An Exploratory Study

Potential Applications of Three-Dimensional Printing in the Hospital Network: An Exploratory Study Bruce Schmidt, Emily Iobst, Philip Horlacher, Michael Pasquale MD, Martin Martino MD Abstract This study sought to explore and evaluate the potential benefits of investing in an on-site three-dimensional (3D) printer for use by the Lehigh Valley Hospital Network (LVHN). Preliminary research was conducted to first determine where and how three-dimensional printing is being utilized in healthcare currently. Interviews were conducted with LVHN physicians and other personnel in an effort to identify cost-effective applications of this technology that could be implemented into the network in a practical manner. Using information gathered from interviews, a general survey was created and administered to 190 physicians in the Department of Surgery at LVHN to both evaluate the degree of interest in 3D printing technology within the network and identify which applications would be most valuable to the physicians. Three main areas of use were identified: 3D model production for preoperative visualization, 3D model production for surgical simulation training and education, and medical device prototyping. The results of the study indicate that the purchase of a 3D printer would be beneficial and utilized by health network personnel. Further education on the capabilities of a 3D printer to the health network personnel is encouraged in order to maximize the profitability of the printer. Keywords Three-dimensional printing, rapid prototyping, patient outcomes, 3D model, custom implants, surgical training Introduction Three-dimensional (3D) printing or rapid prototyping is a process of additive manufacturing that produces physical 3D objects from digital 3D models or other electronic data sources. The process involves the successive layering of many thin sheets of a material (“3D printing”). The object produced can be of virtually any shape or geometry, and composed of a variety of materials including plastics, metals, and resins (Kurenov, Ionita, Sammons, & Demmy, 2015). The size, quality, and degree of detail of the object are dependent upon the printer model, the type of material being used, and the software. Recent advancements in the capabilities of 3D printing technology have allowed for increased integration into the healthcare industry, specifically the surgical arena. Rapid prototyping techniques are being used in conjunction with common medical imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI) for the production of anatomic models and customizable implant devices based on patient data (Kurenov, Ionita, Sammons, & Demmy, 2015). Three main steps are standard in transforming the raw imaging data into a solid 3D model: obtainment of CT or MRI image, generation of Computer-aided Design (CAD) drawing using CAD software, and the printing of the solid 3D model (Rengier et al., 2010). In terms of medical applications, physicians across many specialties at institutions around the world are utilizing rapid prototyping as a diagnostic tool for patient cases with complex anatomical anomalies (Tam, Latham, Brown, & Jakeways, 2014; Igami et al., 2014). In these cases, the use of prototype models can improve diagnostic quality, aid in preoperative planning, and provide intraoperative navigation (Kurenov, Ionita, Sammons, & Demmy, 2015; Yang et al., 2015; Azuma et al., 2014). The benefits associated with the utilization of patient-based models for preoperative planning have been proven in spine, maxillofacial, thoracic, cardiovascular, kidney, lung, and liver surgeries (Yang et al., 2015; Azuma et al., 2014; Kurenov, Ionita, Sammons, & Demmy, 2015; Tam, Latham, Brown, & Jakeways, 2014; Komai et al., 2014; Gildea, 2014; Igami et al., 2014). These models are also used as training tools for teaching and practicing surgical procedures outside the operating room (Stone et al., 2015; Kurenov, Ionita, Sammons, & Demmy, 2015). In addition to models, 3D printing is playing a role in medical prosthesis and custom implant design. Its application in hip, femoral, knee joint, and maxillofacial reconstructive surgeries is well documented (Rengier et al., 2010). In this study, the potential benefits of investing in an on-site 3D printer for use by the Lehigh Valley Hospital Network (LVHN) are explored and evaluated. As an institution that performed over 35,000 surgeries in the past year, LVHN is an ideal market for 3D printing technology. As rapid prototyping becomes increasingly standard in the healthcare industry, such technology is becoming less of a novelty and more of a necessity. In order for LVHN to continue to lead the region in patient care, it is imperative for the network to consider and investigate this technology. Methodology A multi-step procedure consisting of preliminary research, individual interviews, and electronic surveying was followed in order to identify applications of 3D printing being used in healthcare currently, determine which applications could be implemented into LVHN in a practical manner, and evaluate the potential benefits and costs associated with those applications. A prototype model based on patient data was printed using standard industry methods at LVPG Plastic and Reconstructive Surgery. The feasibility and costs of the printing process for the prototype were examined. MEDLINE was searched between January 1, 2010 and June 1, 2015 using the keyword “three-dimensional printing.” This keyword was combined using “AND” with the following terms: “surgery” and “hospital.” The term “rapid prototyping” was searched separately. Additionally, the institutional websites of the top ten hospitals in the U.S. (as ranked in U.S. News & World Report for 2015-2016) were searched in terms of applications of 3D printing. Only studies that have put 3D printing technology into clinical practice were considered. Individual unstructured interviews were conducted with eight LVHN employees. Those employees consisted of physicians, surgical education coordinators, and Information Services (IS) staff. Discussions were focused on cost-effective applications of 3D printing that could be implemented given the resources at LVHN. Notes from the interviews were used in the creation of an electronic survey. The survey was administered to 190 physicians in the Department of Surgery via email. It consisted of three questions: 1. Would a 3D printer be a valuable addition to LVHN? 2a. Do you have any ideas for how 3D printing would enhance your practice currently? 2b. If yes [to 2a], in which of the following areas? The options given for question 2b are listed in Figure 4. Responses were received via email and recorded on a data sheet. Graphical analysis of the survey responses was performed (Figures 2,3,4). No incentive was offered for completing the survey. A model of a patient’s skull with a severe facial fracture was produced by acquiring a CT scan of the patient and converting the 2D image into a digital 3D model using commercial CAD software. A custom implant was designed to correct the fracture using the software as well. The CAD model was generated as a stereolithography (STL) file. The STL file was then sent to a 3D printing vendor for fabrication of the physical model. Patient consent was obtained through HIPPA media release form. The costs associated with the process of vendor printing were noted and compared to the costs of using an on-site printer (Figure 5). Results Based on the preliminary research and individual interviews, three main applications of 3D printing were established: 3D model production for preoperative planning, 3D model production for surgical simulation training and education, and medical device prototyping. The results of the survey provided information about the degree of interest in the purchase of a 3D printer at LVHN as well as where and how network personnel would utilize the technology. 20 out of 190 physicians responded to the survey. Of the sample that participated, 76% of the respondents believe a 3D printer would be a valuable asset in the health network while 14% believe it would not be; 10% were uncertain as to whether or not a 3D printer would be beneficial (Figure 2). 72% of the respondents had ideas for how 3D printing technology would enhance their practice currently; 14% did not have any ideas while the remaining 14% were uncertain (Figure 3). For those that did have ideas, preoperative planning was the most popular application receiving 12 votes. Surgical training and device prototyping received 7 and 8 votes respectively (Figure 4). Respondents were allowed to vote for more than one application. The average cost for a standard 3D printer with the capabilities to produce clinically accurate prototypes using plastics and other resins is approximately $150,000. The average cost for CAD software and licensing is$1,500. These are both one-time costs. The average cost of materials is anywhere from $50 to$100 depending on the type of material. Vendor charges can be anywhere from $500 to$2,500 depending on the manufacturer and the desired prototype to be printed (Figure 5). These costs are general averages based on current market prices for the printing of a plastic skull. Discussion Based on the preliminary research, interviews, and electronic survey, the addition of a 3D printer at LVHN would be beneficial and utilized by hospital staff across several departments. Although survey participation was low (~11%), a decisive majority of physicians in that small sample view 3D printing technology as a potential asset in the areas of preoperative planning, surgical training and education, and medical device prototyping. It is important to note that a relatively significant portion of physicians were uncertain of the capabilities of a 3D printer. Educating hospital staff on the capabilities of this technology would allow for increased use and thus increased profitability. With the help of patient-specific models created using 3D printing technology, LVHN surgeons would be able to simulate complicated surgical steps for complex cases in advance thus allowing them to foresee intraoperative complications. This may result in reduced operating times, less blood loss and transfusion volumes, decreased amount of time the patient is under anesthesia, and shortened length of hospital stay. All of these factors contribute to a more cost-effective use of the operating room as well as improved patient outcomes. These models could also be beneficial in demonstrating and explaining surgical procedures to patients and their families (Kurenov, Ionita, Sammons, & Demmy, 2015; Rengier et al., 2010). Rapid prototyping models could be used as valuable educational tools for use in the Surgical Educational Center by surgical residents and SELECT medical students. These simulated models would allow for safe training of surgical procedures in a realistic manner without the risk of harm to a patient (Stone et al., 2015). Techniques using a multi-material 3D printer to create translucent organ models with realistic visual and tactile sense feedbacks have already been proven successful (Komai et al., 2014). In terms of medical prosthesis and implant design, a 3D printer would allow orthopedic and reconstructive surgeons at LVHN the ability to create custom implants for their patients. The need for customized implants is apparent in cases where patients are outside the standard range with respect to prosthesis size, or have condition-specific special requirements. Custom implants offer improved surgical outcomes and reduced operating time because of patient-specific fitting that matches individual anatomical needs (Rengier et al., 2010). Cost comparison between vendor printing and on-site printing emphasizes the cost-effectiveness of having an on-site printer in the health network versus outsourcing the prints. To produce a model of certain dimensions and materials using a commercial vendor costs substantially more than it would cost to print the same model on-site. This finding is consistent with another study that reported a vendor cost of two to three times the overall cost for printing model pulmonary arteries on-site (Kurenov, Ionita, Sammons, & Demmy, 2015). This study was successful in uncovering the potential benefits of an on-site 3D printer through preliminary research, provider interviews, and a standardized survey. Results showed that a 3D printer would be advantageous for preoperative planning, surgical simulation training and education, and medical device prototyping. In conclusion, investing in a 3D printer is supported as a potential cost-effective way for LVHN to remain on the cutting edge of medical technology as well as improve surgical training and patient outcomes. Acknowledgements Randolph Wojcik, Jr., MD Christian Caputo References Azuma, M., Yanagawa, T., Ishibashi-Kanno, N., Uchida, F., Ito, T., Yamagata, K., . . . Bukawa, H. (2014). Mandibular reconstruction using plates prebent fit rapid prototyping 3-dimensional printing models ameliorates contour deformity. Head & Face Medicine, 10(45), 1-8. doi: 10.1186/1746-160X-10-45 Gildea, T. (2014, Winter). 3D printing: Innovation allows customized airway stents. Respiratory Exchange.12-13 Komai, Y., Sugimoto, M., Kobayashi, T., Ito, M., Sakai, Y., & Saito, N. (2014). Patient-based 3D printed organ model provides tangible surgical navigation: A novel aid to clampless partial nephrectomy. The Journal of Urology, 191(4S), e488. Kurenov, S.N., Ionita, C., Sammons, D., & Demmy, T.L. (2015). Three-dimensional printing to facilitate anatomic study, device development, simulation, and planning in thoracic surgery. The Journal of Thoracic and Cardiovascular Surgery, 149(4), 973-979. http://dx.doi.org/10.1016/j.jtcvs.2014.12.059 Rankin, T.M., Mailey, B., Cucher, D., Giovinco, N.A., Armstrong, D.G., & Gosman, A. (2014). Use of 3D printing for auricular template molds in first stage microtia. Plastic and Reconstructive Surgery, 134(4S-1), 16-17 Rengier, F., Mehndiratta, A., von, T.-K. H., Zechmann, C. M., Unterhinninghofen, R., Kauczor, H.-U., & Giesel, F. L. (2010). 3D printing based on imaging data: review of medical applications. International Journal of Computer Assisted Radiology and Surgery : a Journal for Interdisciplinary Research, Development and Applications of Image Guided Diagnosis and Therapy, 5(4), 335-341. Stone, J., Candela, B., Alleluia, V., Fazili, A., Richards, M., Feng, C., . . . Ghazi, A. (2015). A novel technique for simulated surgical procedures using 3D printing technology [Abstract]. The Journal of Urology, 193(4S), e270. Tam, M., Latham, T., Brown, J.R.I., & Jakeways, M. (2014). Use of a 3D printed hollow aortic model to assist EVAR planning in a case with complex neck anatomy: Potential of 3D printing to improve patient outcome. Journal of Endovascular Therapy, 21, 760-762. doi: 10.1583/14-4810L.1 Igami, T., Nakamura, Y., Hirose, T., Ebata, T., Yokoyama, Y., Sugawara, G., . . . Nagino, M. (2014). Application of a three-dimensional print of a liver in hepatectomy for small tumors invisible by intraoperative ultrasonography: Preliminary experience. World Journal of Surgery, 38, 3163-3166. doi: 10.1007/s00268-014-2740-7 Yang, M., Li, C., Li, Y., Zhao, Y., Wei, X., Zhang, G., . . . Li, M. (2015). Application of 3D rapid prototyping technology in posterior corrective surgery for Lenke 1 adolescent idiopathic scoliosis patients. Medicine, 94(8), 1-8. doi: 10.1097/MD.0000000000000582 3D printing. (n.d.). In Oxford Dictionaries online. Retrieved from http://www.oxforddictionaries.com/us/definition/american_english/3D-printing Appendix Figure 4. Graphical representation of results for question 2b. Figure 5. Overview of 3D printing process including cost comparison between on-site printing and vendor printing for the production of a model skull. Figure 3. Graphical representation of results for question 2a. Figure 2. Graphical representation of results for question 1

La transizione universitaria in matematica come rito di passaggio: dialogo tra educazione matematica e antropologia

Mathematics education has, by its very nature, profound relationship with other fields of research. Among these related fields of research, a prominent place is certainly held by anthropology, as a discipline focused on the study of the human beings. Several studies in mathematics education refer to issues and constructs developed in the field of anthropology. Recently, some scholars tried to analyze the difficulties in the mathematical transition from secondary school to university describing it as a rite of passage. In this paper, we will describe this modeling attempt and its results, but more importantly we will discuss whether and how convincingly the model is used from an anthropological point of view