scholarly journals Evaluation of smartphone-integrated magnetometers in detection of safe electromagnetic devices for use near programmable shunt valves: a proof-of-concept study

2021 ◽  
pp. 1-8
Author(s):  
Smruti K. Patel ◽  
Jorge Zamorano-Fernández ◽  
Carlie McCoy ◽  
Jesse Skoch
Keyword(s):  
Experimental Data ◽  
Magnetic Flux Density ◽  
Proof Of Concept ◽  
Saturation Point ◽  
Electromagnetic Devices ◽  
Sensor Saturation ◽  
Programmable Valve ◽  
Smartphone Sensors ◽  
Programmable Valves ◽  
Tolerance Testing

OBJECTIVE External magnetic forces can have an impact on programmable valve mechanisms and potentially alter the opening pressure. As wearable technology has begun to permeate mainstream living, there is a clear need to provide information regarding safety of these devices for use near a programmable valve (PV). The aim of this study was to evaluate the magnetic fields of reference devices using smartphone-integrated magnetometers and compare the results with published shunt tolerances. METHODS Five smartphones from different manufacturers were used to evaluate the magnetic properties of various commonly used (n = 6) and newer-generation (n = 10) devices using measurements generated from the internal smartphone magnetometers. PV tolerance testing using calibrated magnets of varying field strengths was also performed by smartphone magnetometers. RESULTS All tested smartphone-integrated magnetometers had a factory sensor saturation point at around 5000 µT or 50 Gauss (G). This is well below the threshold at which a magnet can potentially deprogram a shunt, based on manufacturer reports as well as the authors’ experimental data with a threshold of more than 300 G. While many of the devices did saturate the smartphone sensors at the source, the magnetic flux density of the objects decreases significantly at 2 inches. CONCLUSIONS The existence of an upper limit on the magnetometers of all the smartphones used, although well below the published deprogramming threshold for modern programmable valves, does not allow us to give precise recommendations on those devices that saturate the sensor. Based on the authors’ experimental data using smartphone-integrated magnetometers, they concluded that devices that measure < 40 G can be used safely close to a PV.

scholarly journals Incidence and management of subdural hematoma/hygroma with variable- and fixed-pressure differential valves: a randomized, controlled study of programmable compared with conventional valves

1999 ◽  
Vol 7 (4) ◽  
pp. E8 ◽  
Author(s):  
Peter W. Carmel ◽  
A. Leland Albright ◽  
P. David Adelson ◽  
Alexa Canady ◽  
Peter Black ◽  
...  
Keyword(s):  
Randomized Trial ◽  
Subdural Hematoma ◽  
Control Valve ◽  
Treatment Modalities ◽  
Controlled Study ◽  
Opening Pressure ◽  
Programmable Valve ◽  
Significant Difference ◽  
Fluid Collections ◽  
Programmable Valves

Shunt systems with differential pressure valves are prone to the complications of overdrainage. A programmable valve permits adjustment of the opening pressure of the valve. In this paper the authors report the incidence of subdural fluid collections in a randomized trial of programmable compared with conventional valves, and they describe methodologies used in management of this complication. A multiinstitutional, prospective, randomized trial of the Codman Hakim programmable valve and conventional fixed-pressure valves was undertaken. Two classes were defined: “new” and “replacement” valves. Randomization of the type of valve in each group was performed at each study site. Clinical and radiological studies were required at fixed intervals over a 104-week period. All complications were reported. The experimental valves were required to be reprogrammed after magnetic resonance imaging studies, but all other decisions regarding pressure setting were left to each investigator. Three hundred seventy-seven patients were randomized; 194 were treated with a programmable valve and 183 with a fixed-pressure valve. The two groups were statistically similar in demographic composition, as were the “new” and “replacement” categories. The investigators made 540 valve pressure changes (five per patient; range one-41 changes). More than half of the reprogramming adjustments were made in the first 3 months postplacement; 70% were made within 6 months. More than half of all reprogramming adjustments were required in a group of 30 patients. Four treatment modalities were observed: 1) 30% of the fluid collections resolved spontaneously (25% in the patients with programmable valves and 36.3% in those with conventional valves) and were largely found to be hygromas in infants and children; 2) four subdural fluid collections were unresolved and under observation; 3) the subdural hematoma was drained and the shunt removed (in 8.3% of patients with the programmable valve and 36.3% of those with the control valve); 4) the pressure of programmable valve was raised in 58% of patients (seven of 12), and this increase in opening pressure was a feature used by investigators to affect treatment. There was no significant difference in the incidence of subdural fluid collections between the programmable and fixed-pressure valve treatment groups. The programmable feature provided a considerable advantage in treatment when subdural collections occurred.

Coordinate Control of Energy-Saving Programmable Valves

2003 ◽  
Author(s):  
Song Liu ◽  
Bin Yao
Keyword(s):  
Energy Saving ◽  
Controller Design ◽  
Tracking Error ◽  
Adaptive Robust Control ◽  
Control Technique ◽  
Coordinate Control ◽  
Side Pressure ◽  
Programmable Valve ◽  
Pressure Dynamics ◽  
Programmable Valves

The energy-saving programmable valve, a unique combination of five independent cartridge valves, not only decouples the control of meter-in and meter-out flows but also provides the ability of precisely controlling cross-port flows for energy-saving purpose. Our previous works have already shown that the tremendous control flexibility gained by the proposed hardware re-configuration enables one not only to achieve precision control of the cylinder motion but also to decrease the energy usage significantly through actively utilizing the potential and kinetic energy of the load in accomplishing certain tasks such as smooth stopping. However, the control of such an essentially multi-input valve system to achieve the above objectives is far from trivial. In our previous works, a constant off-side pressure was assumed in the controller design for simplicity. This assumption may not be realistic in certain circumstances where the off-side pressure may vary from the assumed constant pressure significantly, especially right after the change of working mode. As a result, though the controller design is simplified, larger tracking error results during the transients. This paper presents an improved way to coordinately control the five independent valves by incorporating the off-side pressure dynamics into the controller design. The Adaptive Robust Control technique is applied to guarantee the stability and tracking performance in the presence of large system parameter variations and disturbances. Simulation and experimental results are shown to verify the much improved control performance of the presented coordinate control strategy.

A FINITE ELEMENT METHOD FOR MODELING OF ELECTROMAGNETIC PROBLEMS

2020 ◽  
pp. 25-31
Author(s):  
Vuong
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Magnetic Flux Density ◽  
Analytic Method ◽  
Electrical System ◽  
Electromagnetic Problems ◽  
Magnetic Circuits ◽  
Electromagnetic Devices ◽  
Electrical Devices ◽  
Element Method

Electromagnetic devices are present everywhere in our daily life. In particular, they extremely play an important role  in the fields of the electrical system. Therefore, the modeling and analyzing the electromagetic problems become currently a matter of concern and topicality for researchers and designers of electrical devices. This paper introduces a finite element method to compute accurate distributions of leakage and fringing fluxes with air-gap variations, and eddy current losses of the magnetic circuits, that cannot generally be solved by a direct analytic method. The method is approached for the magnetic flux density formulation.

scholarly journals Estimation of Energy Losses in Nanocrystalline FINEMET Alloys Working at High Frequency

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7745
Author(s):  
Lucian-Gabriel Petrescu ◽  
Maria-Catalina Petrescu ◽  
Emil Cazacu ◽  
Catalin-Daniel Constantinescu
Keyword(s):  
High Frequency ◽  
Core Loss ◽  
Magnetic Core ◽  
Soft Magnetic Materials ◽  
Magnetic Flux Density ◽  
Nominal Composition ◽  
Magnetic Alloy ◽  
Soft Magnetic ◽  
Soft Magnetic Alloy ◽  
Electromagnetic Devices

Soft magnetic materials are at the core of electromagnetic devices. Planar transformers are essential pieces of equipment working at high frequency. Usually, their magnetic core is made of various types of ferrites or iron-based alloys. An upcoming alternative might be the replacement the ferrites with FINEMET-type alloys, of nominal composition of Fe73.5Si13.5B9Cu3Nb1 (at. %). FINEMET is a nanocrystalline material exhibiting excellent magnetic properties at high frequencies, a soft magnetic alloy that has been in the focus of interest in the last years thanks to its high saturation magnetization, high permeability, and low core loss. Here, we present and discuss the measured and modelled properties of this material. Owing to the limits of the experimental set-up, an estimate of the total magnetic losses within this magnetic material is made, for values greater than the measurement limits of the magnetic flux density and frequency, with reasonable results for potential applications of FINMET-type alloys and thin films in high frequency planar transformer cores.

scholarly journals Iron Losses in Electromagnetic Devices: Nonlinear Adaptive MEC & Dynamic Hysteresis Model

2017 ◽  
Author(s):  
Oualid Messal ◽  
Frédéric Dubas ◽  
Raouf Benlamine ◽  
Afef Kedous-Lebouc ◽  
Christian Chillet ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Computation Time ◽  
Magnetic Flux Density ◽  
Hysteresis Model ◽  
Electromagnetic Devices ◽  
Iron Losses ◽  
Radial Flux ◽  
Interior Permanent Magnet ◽  
Hybrid Fuel Cell Vehicles

In this paper, an original approach allowing the determination of the iron losses in the electromagnetic devices is presented. This new approach exploits the Loss Surface (LS) hysteresis model and the magnetic flux density waveforms resulting from a generalized nonlinear adaptive magnetic equivalent circuit (MEC) using a mesh-based formulation in two-dimensional (2-D) or quasi three-dimensional (3-D). The model coupling has been applied to a 18-slots/16-poles radial-flux interior permanent-magnet (PM) synchronous machine (PMSM) dedicated to automotive applications, mainly for electric/hybrid/fuel cell vehicles (EVs/HEVs/FCVs). The obtained results have been compared with those made retrospectively in the 2-D transient finite-element (FE) Flux. The influence of the MEC discretization on the iron loss calculation and the electromagnetic performances has been analyzed. The computation time is divided by 3/2 with an error less than 7 %.

scholarly journals Electrochemically Triggered Dynamics Within a Hybrid Metal-Organic Electrocatalyst

2019 ◽  
Author(s):  
Nina Heidary ◽  
Mathieu Morency ◽  
Daniel Chartrand ◽  
Khoa Ly ◽  
Radu Iftimie ◽  
...  
Keyword(s):  
Experimental Data ◽  
Metal Organic Frameworks ◽  
Proof Of Concept ◽  
Reaction Intermediates ◽  
Carboxylate Ligands ◽  
Guest Species ◽  
Raman And Infrared Spectroscopy ◽  
Metal Organic ◽  
Responsive Behavior

<p> A wide array of systems, ranging from enzymes to synthetic catalysts, exert adaptive motifs to maximize their functionality. In a related manner, select metal-organic frameworks (MOFs) and related systems exhibit structural modulations under stimuli such as the infiltration of guest species. Probing their responsive behavior <i>in-situ</i> is a challenging but important step towards understanding their function and subsequently building from there. In this report, we investigate the dynamic behavior of an electrocatalytic Mn-porphyrin containing MOF system (Mn-MOF). We discover, using a combination of electrochemistry and <i>in-situ</i> probes of UV-Vis absorption, resonance Raman and infrared spectroscopy, a restructuration of this system via a reversible cleavage of the porphyrin carboxylate ligands under an applied voltage. We further show, by combining experimental data and DFT calculations, as a proof of concept, the capacity to utilize the Mn-MOF for electrochemical CO<sub>2</sub> fixation and to spectroscopically capture the reaction intermediates in its catalytic cycle. The findings of this work and methodology developed opens opportunities in the application of MOFs as dynamic, enzyme-inspired electrocatalytic systems.</p>

scholarly journals Comparative durability and costs analysis of ventricular shunts

2019 ◽  
Vol 130 (4) ◽  
pp. 1252-1259 ◽  
Author(s):  
Nitin Agarwal ◽  
Ahmed Kashkoush ◽  
Michael M. McDowell ◽  
William R. Lariviere ◽  
Naveed Ismail ◽  
...  
Keyword(s):  
Randomized Clinical Trials ◽  
Interquartile Range ◽  
Adult Patients ◽  
Additional Patient ◽  
Shunt Revision ◽  
Similar Frequency ◽  
Programmable Valve ◽  
Programmable Valves ◽  
Supply Costs

OBJECTIVEVentricular shunt (VS) durability has been well studied in the pediatric population and in patients with normal pressure hydrocephalus; however, further evaluation in a more heterogeneous adult population is needed. This study aims to evaluate the effect of diagnosis and valve type—fixed versus programmable—on shunt durability and cost for placement of shunts in adult patients.METHODSThe authors retrospectively reviewed the medical records of all patients who underwent implantation of a VS for hydrocephalus at their institution over a 3-year period between August 2013 and October 2016 with a minimum postoperative follow-up of 6 months. The primary outcome was shunt revision, which was defined as reoperation for any indication after the initial procedure. Supply costs, shunt durability, and hydrocephalus etiologies were compared between fixed and programmable valves.RESULTSA total of 417 patients underwent shunt placement during the index time frame, consisting of 62 fixed shunts (15%) and 355 programmable shunts (85%). The mean follow-up was 30 ± 12 (SD) months. The shunt revision rate was 22% for programmable pressure valves and 21% for fixed pressure valves (HR 1.1 [95% CI 0.6–1.8]). Shunt complications, such as valve failure, infection, and overdrainage, occurred with similar frequency across valve types. Kaplan-Meier survival curve analysis showed no difference in durability between fixed (mean 39 months) and programmable (mean 40 months) shunts (p = 0.980, log-rank test). The median shunt supply cost per index case and accounting for subsequent revisions was $3438 (interquartile range $2938–$3876) and $1504 (interquartile range $753–$1584) for programmable and fixed shunts, respectively (p < 0.001, Wilcoxon rank-sum test). Of all hydrocephalus etiologies, pseudotumor cerebri (HR 1.9 [95% CI 1.2–3.1]) and previous shunt malfunction (HR 1.8 [95% CI 1.2–2.7]) were found to significantly increase the risk of shunt revision. Within each diagnosis, there were no significant differences in revision rates between shunts with a fixed valve and shunts with a programmable valve.CONCLUSIONSLong-term shunt revision rates are similar for fixed and programmable shunt pressure valves in adult patients. Hydrocephalus etiology may play a significant role in predicting shunt revision, although programmable valves incur higher supply costs regardless of initial diagnosis. Utilization of fixed pressure valves versus programmable pressure valves may reduce supply costs while maintaining similar revision rates. Given the importance of developing cost-effective management protocols, this study highlights the critical need for large-scale prospective observational studies and randomized clinical trials of ventricular shunt valve revisions and additional patient-centered outcomes.

scholarly journals Chronic subdural hematoma treatment with adjustment of programmable valve in idiopathic normal pressure hydrocephalus patient: a case report

2014 ◽  
Vol 33 (02) ◽  
pp. 139-141
Author(s):  
Matheus Fernandes de Oliveira ◽  
Rodolfo Casimiro Reis ◽  
Fernando Campos Gomes Pinto ◽  
José Marcus Rotta
Keyword(s):  
Cerebrospinal Fluid ◽  
Normal Pressure Hydrocephalus ◽  
Subdural Hematoma ◽  
Chronic Subdural Hematoma ◽  
Normal Pressure ◽  
Idiopathic Normal Pressure Hydrocephalus ◽  
Benign Condition ◽  
Programmable Valve ◽  
Programmable Valves ◽  
Normal Pressure Hydrocephalus Patient

AbstractChronic subdural hematoma (CSDH) is a common entity in daily neurosurgical practice. It is considered a benign condition. Idiopathic normal pressure hydrocephalus (INPH) is characterized by gait disturbance, dementia and/or urinary incontinence added to dilation of ventricular system due to disturbance of cerebrospinal fluid (CSF) circulation with normal CSF pressure. We describe an experience of a conservative treatment of subdural hematoma based in the physiopathology and ability to control the pressure in programmable valves. The adjustment of programmable valves in the treatment of INPH allow us the therapeutic control of hydrocephalus and an important tool to manage complications, especially overshunting and undershunting.

scholarly journals The binding of human lactoferrin to mouse peritoneal cells.

1976 ◽  
Vol 144 (6) ◽  
pp. 1568-1580 ◽  
Author(s):  
J L Van Snick ◽  
P L Masson
Keyword(s):  
Experimental Data ◽  
Cytochrome C ◽  
Inhibitory Activity ◽  
Reticuloendothelial System ◽  
Affinity Constant ◽  
Beef Heart ◽  
Inhibiting Activity ◽  
Specific Receptor ◽  
Saturation Point ◽  
Peritoneal Cells

Human iron-saturated Lf (FeLf), which was labeled with 125I or 50Fe, was found to combine with the membrane of mouse peritoneal cells (MPC) which consisted of 70% macrophages. The following experimental data suggested the involvement of a specific receptor. (a) The binding of FeLf to MPC reached a saturation point. (b) The binding of radioactive FeLf was inhibited by preincubating the cells with cold FeLf but not with human Tf, human aggregated and nonaggregated IgG, or beef heart cytochrome c (c) Succinylation and carbamylation of FeLf resulted in a loss of its inhibiting activity on the binding of radioactive FeLf. Removal of neuraminic acid from FeLf increased its inhibitory activity. (d) The ability of apoLf to inhibit the binding of FeLf to MPC was significantly lower than that of FeLf. The existence of a Lf receptor capable of concentrating Lf released from neutrophils on the membrane of macrophages could explain the apparent blockade of the release of iron from the reticuloendothelial system, which accounts for the hyposideremia of inflammation. A receptor for FeLf was also found on mouse peritoneal lymphocytes. The affinity constant of FeLf for both lymphocytes and macrophages was 0.9 X 12(6) liter/mol. Howerver, macrophages bound three times more FeLf molecules (20 X 10(6)) per cell than did lymphocytes (7 X 10(6)).

Programmable shunt valve affected by exposure to a tablet computer

2012 ◽  
Vol 10 (2) ◽  
pp. 118-120 ◽  
Author(s):  
Jennifer Strahle ◽  
Béla J. Selzer ◽  
Karin M. Muraszko ◽  
Hugh J. L. Garton ◽  
Cormac O. Maher
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Flux Density ◽  
Performance Level ◽  
Magnetic Flux Density ◽  
Tablet Computer ◽  
Shunt Valve ◽  
Tablet Devices ◽  
Tablet Device ◽  
Programmable Valves

Object The authors investigated the effect of a tablet computer on performance-level settings of a programmable shunt valve. Methods Magnetic field strength near the tablet computer with and without a cover was recorded at distances between 0 and 100 mm. Programmable valves were exposed to the tablet device at distances of less than 1 cm, 1–2.5 cm, 2.5–5 cm, 5–10 cm, and greater than 10 cm. For each distance tested, the valves were exposed 100 times to the tablet with the cover, resulting in 500 total valve exposures. The tablet alone, without the cover, was also tested at distances of less than 1 cm for 30 valve exposures. Changes in valve performance-level settings were recorded. Results The maximum recorded magnetic flux density of a tablet with a cover was 17.0 mT, and the maximum recorded magnetic flux density of the tablet alone was 7.6 mT. In 100 exposures at distances between 0 and 1 cm, 58% of valves had different settings following exposure. At distances greater than 1 cm but less than 2.5 cm, 5% of valves in 100 exposures had setting changes. Only a single setting change was noted in 100 exposures at distances greater than 2.5 cm but less than 5 cm. No setting changes were noted at distances greater than 5 cm, including 100 exposures between 5 and 10 cm, and 100 exposures of more than 10 cm. For the 30 valve exposures to the tablet without a cover, 20 valve performance-level changes (67%) were noted. Conclusions Based on these results, exposure to tablet devices may alter programmable shunt valve settings.

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