Coil Group Research Articles

Anterior Optic Pathway Compression Due to Internal Carotid Artery Aneurysms: Neurosurgical Management and Outcomes.

Background and PurposeCompression of the anterior optic pathway results in visual deficits that can lead to the detection of unruptured aneurysms in the internal carotid artery (ICA). The general types of treatment modalities for aneurysms and visual deficits include surgery and endosaccular coiling. This study retrospectively analyzed and compared the resolution of visual deficits following surgery or endosaccular coiling.MethodsWe reviewed data on 33 patients with unruptured ICA aneurysms who presented with visual field deficits caused by mass effects over the anterior optic pathway. Statistical analyses were performed to identify the variables associated with the recovery of visual symptoms.ResultsEighteen patients underwent aneurysm clipping, 2 underwent bypass surgery with endovascular trapping, and 2 underwent endovascular trapping without bypass surgery (group A). Ten patients received endosaccular coiling (group B). The visual outcomes included the following: in group A, 17 patients (73.9%) demonstrated improvement and 6 patients (26.1%) demonstrated no changes or worse outcomes; in group B, 2 patients (20.0%) demonstrated improvement and 8 patients (80.0%) demonstrated no changes or worse outcomes. Group A was associated with a higher rate of favorable outcome than group B (P = 0.007). According to the multivariate analysis, treatment without endosaccular coiling (group A) was the only variable significantly associated with improvement of visual outcome (P = 0.005; OR = 28.523; 95% CI = 2.683-303.171).ConclusionsTreatment modality was the only predictor of improvement in visual deficits. Treatment without endosaccular coiling resulted in visual improvement significantly more often in comparison with endosaccular coiling.

Electrical design of the BUSSARD inverter system for ASDEX upgrade saddle coils

A set of 16 in-vessel saddle coils is installed in the ASDEX Upgrade (AUG) nuclear fusion experiment for mitigation of edge localized modes (ELM) and feedback control of resistive wall modes (RWM). The coils were driven by DC current only during previous campaigns. Now, a new inverter system “BUSSARD” (German abbr. for “Bayerischer Umrichter, schnell schaltend für AUGs rasche Drehfelder”, translated: “bavarian fast switching inverter for AUG's fast rotating fields”) is built for the experiment. A four-phase system has been assembled to simultaneously operate up to 4 groups of coils consisting of up to 4 serial-connected coils each. The maximum current is 1.3kA with a ripple in the range of 7% and the frequency is variable between DC and approx. 100Hz. The switching frequency is variable between approximately 3 and 10kHz. As a first application, rotating fields are generated. The system can be enhanced in two stages to 16-phase operation with a bandwidth of 500Hz and a 24 phase system with a bandwidth of up to 3kHz.

P68. Theta burst stimulation effects on visual cortex: Dependency of coil geometry

Transcranial magnetic theta burst stimulation (TBS) is an efficient method to modulate excitability of the motor cortex. There have been some demonstrations of TBS effects in non-motor cortical regions, but it is still not clear whether the scheme from motor cortex, i.e. inhibitory effects by continuous TBS (cTBS) and excitatory effects by intermittent TBS (iTBS) can be transferred to other cortical regions. Applying TBS with 100% of individual phosphene threshold (PT) intensity on visual cortex with a figure-of-eight coil we observed a modulation of PT neither with cTBS nor with iTBS (Bruckner & Kammer 2015, this conference). As our findings were in contrast to Franca et al. (2006), who described an increase in PT following cTBS (80% of individual PT) we aimed to directly replicate their results. To that end we compare cTBS effects elicited with a focal figure-of-eight-coil with those elicited by a simple, less focal round coil, since Franca et al. (2006) were using a round coil. In a between-group-design continuous TBS (cTBS, 600 pulses) with 80% of individual PT intensity was applied using either a figure-of-eight-coil or a round coil. PT was measured before and 2 min after cTBS application. So far (October 2014), 14 subjects (7 men, mean age 24.6 ± 3.7 years) participated in the figure-of-eight-coil-group and 4 subjects in the round coil-group. Mean baseline PT value of the figure-of-eight-coil group was 39.3 ± 7.3% of maximum stimulator output. After cTBS PT values slightly decreased (trend to significance in paired two-tailed t -test, t = 2.07, p = 0.059). First visual inspection of the round coil group data indicate that cTBS applied with 80% of individual PT might increase PT, comparable to Franca et al. (2006). We will complete the data set up to 16 subjects in each group. CTBS effects in the visual system seem to depend on the focality of the applied electromagnetic field varied by the different coil geometries used.

Treatment of unruptured vertebral dissecting aneurysms: internal trapping or stent-assisted coiling

Purpose: Endovascular treatment is an attractive approach for the treatment of unruptured vertebral dissecting aneurysms, and includes internal trapping and stent-assisted coil embolization. However, the optimal therapy remains debatable. We reviewed our experience with both endovascular treatment modalities and compared the safety, efficacy, and short-term outcomes for each approach. Materials and Methods: We retrospectively reviewed 65 consecutive patients with unruptured vertebral dissecting aneurysms who underwent endovascular treatment between January 2003 and January 2014. 24 patients underwent endovascular internal trapping (group A) while 41 patients underwent stent-assisted coiling (group B). Thirteen patients underwent single stent with coiling while 28 patients underwent double or three stent-assisted coiling. Short-term outcomes were evaluated using the modified Rankin Scale. Results: A favorable clinical outcome was achieved in 58 of 65 patients. Procedure-related complications included ischemic symptoms (n = 6) and recurrence (n = 4). There was no statistical difference in modified Rankin Scale scoring between groups. Group A patients had more ischemia symptoms compared with group B patients (p = 0.043), Group B patients had higher recurrence rates compared with group A patients, but the difference had no statistical significance (p = 1.00). However, recurrence only occurred in patients who underwent stent-assisted coiling alone (p = 0.046). Conclusion: Stent-assisted coiling for unruptured vertebral dissecting aneurysms may maintain artery patency. Multilayer disposition of stents with coils may decrease complications and facilitate aneurysm occlusion. Larger, prospective studies are necessary to determine the long-term outcomes of reconstructive therapy.

Pre-operative embolisation of spinal metastasis: technique, complication rate and outcome-clinical experience.

Pre-operative embolisation of metastatic spinal tumours has the potential to decrease intra-operative blood loss. Intra-operative blood loss is multifactorial and one factor may be the embolisation technique used. The purpose of this study was to retrospectively analyse the effect of three different pre-operative embolisation techniques on intra-operative blood loss, complication rate and tumour aetiology in patients treated with a corpectomy and dorsoventral stabilisation at our institution. We conducted a retrospective analysis of embolisation procedures for vertebral metastases performed from January 2002 to December 2011. Only pre-operatively embolised patients treated by a single-level hemicorpectomy or corpectomy procedure from T4-L5, including posterior spinal stabilisation using pedicle screws, were included. All patient charts and examinations were analysed regarding the embolisation technique, gender, age, primary tumour, time between the embolisation and surgery, intra-operative blood loss, intra-operative transfusions and complications related to embolisation. We identified a total of 46 patients, 25 male and 21 female patients. The mean age at the time of surgery was 66 years (range 39-84 years). The tumours treated were: 15 (33%) renal cell carcinomas, six (13%) breast carcinomas, five (11%) lung carcinomas, five (11%) urothelial carcinomas, four (9%) myelomas and 11 (24%) miscellaneous types including rectal carcinoma, thymoma and melanoma. Embolisation with coils was performed in 23 patients, particles were used in six and a combination of coils and particles in 18. The mean time between the embolisation and surgery was 23 hours (range 80-4,430 minutes). The median overall intra-operative estimated blood loss (EBL) was 2,300 ml (range 500-15,000 ml). In patients embolised with coils and particles, EBL was 2,200 ml compared to 1,450 ml in patients embolised with particles and 2,500 ml in the coil group. No statistically significant differences between the three groups could be detected. There were no complications related to the embolisation techniques. Pre-operative embolisation of spinal metastases using coils, particles or a combination of both is a safe and reproducible procedure. In our cohort we reported no complications during the three different embolisation techniques. No statistically significant difference regarding blood loss between the three embolisation techniques could be detected. Our data confirm existing studies concerning the control of intra-operative blood loss using different embolisation techniques. The benefit of embolisation with a combination of coils and particles compared to embolisation with particles only is questionable.

Quantitative study of liver magnetic resonance spectroscopy quality at 3T using body and phased array coils with physical analysis and clinical evaluation.

This study aims to investigate the quality difference of short echo time (TE) breathhold 1H magnetic resonance spectroscopy (MRS) of the liver at 3.0T using the body and phased array coils, respectively. In total, 20 pairs of single-voxel proton spectra of the liver were acquired at 3.0T using the phased array and body coils as receivers. Consecutive stacks of breathhold spectra were acquired using the point resolved spectroscopy (PRESS) technique at a short TE of 30 ms and a repetition time (TR) of 1500 ms. The first spectroscopy sequence was “copied” for the second acquisition to ensure identical voxel positioning. The MRS prescan adjustments of shimming and water suppression, signal-to noise ratio (SNR), and major liver quantitative information were compared between paired spectra. Theoretical calculation of the SNR and homogeneity of the region of interest (ROI, 2 cm×2 cm×2 cm) using different coils loaded with 3D liver electromagnetic model of real human body was implemented in the theoretical analysis. The theoretical analysis showed that, inside the ROI, the SNR of the phase array coil was 2.8387 times larger than that of body coil and the homogeneity of the phase array coil and body coil was 80.10% and 93.86%, respectively. The experimental results showed excellent correlations between the paired data (all r > 0.86). Compared with the body coil group, the phased array group had slightly worse shimming effect and better SNR (all P values < .01). The discrepancy of the line width because of the different coils was approximately 0.8 Hz (0.00625 ppm). No significant differences of the major liver quantitative information of Cho/Lip2 height, Cho/Lip2 area, and lipid content were observed (all P values >0.05). The theoretical analysis and clinical experiment showed that the phased array coil was superior to the body coil with respect to 3.0T breathhold hepatic proton MRS.

Fabrication and Test of an 8-T Superconducting Split Magnet System With Large Crossing Warm Bore

A conduction-cooled superconducting split magnet system with large crossing warm bore has been successfully constructed in our laboratory for material processing applications. The magnet system design was described in a previous paper. The magnet is composed of six NbTi low temperature superconducting coils, which generate 5.5-T central magnetic field and two Bi2223/Ag high temperature superconducting (HTS) insert coils, which generate 2.5-T central magnetic field and assembled in the form of split coil groups. The magnet has a 136-mm split gap to accommodate the crossing warm bore of 100 mm in diameter. The magnet system is cooled by two GM cryocoolers. The initial cooldown takes 9.2 days and the final temperature of the magnet is about 4.0 K. The HTS coils and NbTi coils are to be operated in the driven mode with two independent power supplies, under the operating currents of 200 A (HTS) and 139 A (NbTi), respectively. The magnet is successfully powered up to 8 T with a the ramp time of 290 min. In this paper, the fabrication and test of the superconducting split magnet system are presented.

Oclusão Percutânea da Persistência do Ducto Arterioso

Introducao: A persistencia do ducto arterioso e uma condicao congenita de alta morbidade, especialmente em recem-nascidos prematuros de extremo baixo peso, representando 5 a 10% das cardiopatias congenitas. Nosso objetivo foi descrever as abordagens realizadas em hospital de referencia para o tratamento da persistencia do ducto arterioso com o metodo percutâneo de oclusao. Metodos: Foi realizado estudo retrospectivo do tratamento transcateter da persistencia do ducto arterioso no periodo de abril de 2008 a abril de 2010. Resultados: Foram revisados 47 casos, a maioria (78,8%) tratada com molas Flipper®; os demais tratados com a protese Amplatzer®. A configuracao morfologica ductal foi do tipo A de Krichenko em 89,4% (34 no grupo molas Flipper® e 8 no grupo Amplatzer®), tipo D em 6,4% (2 no grupo molas Flipper® e 1 no grupo Amplatzer®) e tipo E em 4,2% (1 em cada grupo) dos pacientes. Os diâmetros minimos pre-cateterismo foram de 2,6 ± 0,8 mm e 3,8 ± 1,6 mm para os grupos de molas Flipper® e Amplatzer®, respectivamente. Obteve-se oclusao imediata total do defeito na angiografia de controle em 72,3% dos pacientes tratados. Sete pacientes tratados com molas Flipper® receberam molas adicionais e os tratados com protese Amplatzer® mostraram apenas shunts residuais minimos em dois casos. Nao ocorreram complicacoes do procedimento. No acompanhamento apos a alta, um paciente permaneceu com minimo shunt residual a ecografia, 45 dias apos o cateterismo. Conclusoes: A oclusao da persistencia do ducto arterioso por metodo percutâneo tem-se mostrado segura e efetiva na maioria dos casos.

TiN films deposition inside stainless-steel tubes using magnetic field-enhanced arc ion plating

A magnetic field-enhanced arc ion plating (MFE-AIP) is utilized to deposit TiN films on the inner wall of a stainless-steel tube with inner diameter 36 mm and length from 108 to 288 mm. Three groups of magnetic field coils are designed and located at different positions, to produce axial magnetic field to focus and to guide the arc plasma beam to spread along the center axial direction of the tubular workpiece. Samples of AISI 304 stainless steel are horizontally placed inside the tube to investigate the structure and performance of the films. A pulse bias is applied to the substrate to accelerate the plasma. The structure, surface morphology, cross-sectional image, hardness and wear-resistant properties as a function of the position inside the tubes are investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), nanoindenter, friction-tester, respectively. The results show that the film structures change from a single TiN phase into mixed phases of TiN and Ti2N with the increase in the distance to the tube entrance. The thickness, hardness and sliding friction coefficient of the films decrease with the increase in the distance to the tube entrance. The magnetic field-enhanced arc ion plating is shown to be an effective tool to treat the inner surface of stainless-steel tubes.

Axial Magnetic Field Distribution Simulation and Optimization in Rotating Magnetron Sputtering System

The primary goal of this study is to optimize the dynamic axial magnetic field distribution in magnetron sputtering system, guiding the target ions to project directly to the substrate. A group of electromagnetic coils were set up to generate an auxiliary axial magnetic field. The configuration of axial magnetic field in different electrifying modes on coils were simulated using numerical integration. Based on the general theoretical results, this paper proposed an optimization of coil arrangement and electrifying modes for a C-shape direct current(DC) magnetron. A 3D model of the coils was set up and the finite element analysis results verified the accuracy of theoretical results. Consequently, this study proposed an arrangement and electrified scheme of electromagnetic coils to provide a dynamic auxiliary axial magnetic field, which could match with the shape and movement of the primary magnetron.

Use of coils in conjunction with the pipeline embolization device for treatment of intracranial aneurysms.

Coiling in conjunction with Pipeline embolization device (PED) placement could provide immediate dome protection and an intraaneurysmal scaffold to prevent device prolapse for intracranial aneurysms with high rupture risk and complex anatomy. To report results after treatment of aneurysms with PED with coils (PED+coils group) or without (PED-only group) at a single-institution. In this case-controlled study, records of patients who underwent PED treatment between 2011 and 2013 were retrospectively reviewed. Twenty-nine patients were treated with PED+coils and 75 with PED-only. No statistically significant between-group differences were found in terms of age, sex, aneurysm location, medical comorbidities, and length of follow-up. Aneurysms treated by PED+coils were larger (16.3 mm vs 12.4 mm, P=.02) and more likely to be ruptured (20.7% vs 1.3%, P=.001) or dissecting (34.5% vs 9.3%, P=.002). PED deployment was successful in all cases. At the latest follow-up (mean, 7.8 months), complete aneurysm occlusion was achieved in a higher proportion of the PED+coils group (93.1% vs 74.7%, P=.03). Device foreshortening/migration occurred in 4 patients in the PED-only group and none in the PED+coils group. Fewer patients required retreatment in the PED+coils group (3.4% vs 16.0%, P=.71). Rates of neurological complications (10.3% PED+coils vs 8.0% PED-only, P=.7) and favorable outcome (modified Rankin Scale score=0-2; 93.1% PED+coils vs 94.7% PED-only, P=.6) were similar. PED+coils may be a safe and effective treatment for aneurysms with high risk of rupture (or rerupture) and complex anatomy. Coiling in conjunction with PED placement provided a higher aneurysm occlusion rate and reduced the need for retreatment.

Prospective, Randomized Study of Coil Embolization versus Surefire Infusion System during Yttrium-90 Radioembolization with Resin Microspheres

PurposeTo compare standard coil embolization versus the use of an antireflux microcatheter (ARM) in patients undergoing planning angiography before selective internal radiation therapy (SIRT). Materials and MethodsA prospective, single-center trial was performed in which 30 patients were randomly assigned to undergo SIRT with coil embolization or the use of an ARM. The coil group underwent detachable coil embolization of nontarget vessels, and the ARM group underwent infusion of macroaggregated albumin with use of an ARM system, without coil embolization. Single-photon emission computed tomography (CT)/CT was then performed to assess for nontarget distribution. The primary endpoint was fluoroscopy time during planning angiography. Secondary endpoints included deployment time, total procedure time, radiation dose–area product, contrast agent used, and adverse events. Endpoints were evaluated during planning angiography and SIRT. ResultsOver a 9-month period, 30 consecutive patients were randomized at a 1:1 ratio between coil embolization and ARM groups. Technical success rates were 100% in both groups. Mean fluoroscopy time was significantly reduced in the ARM group versus the coil embolization group (1.8 min [range, 0.4–4.9 min] vs 6.0 min [range, 1.9–15.7 min]; P = .002). The planning procedure time (P < .001), deployment time (P < .001), dose–area product (P = .04), and amount of contrast agent used (P < .001) were also significantly less in the ARM group than in the coil embolization group. No nontarget distribution was detected in either group. There was no difference between groups in dose delivered on the day of SIRT (P = .71). There were no major or minor adverse events at 30 days. ConclusionsThe use of an ARM during planning angiography can significantly reduce fluoroscopy time, procedure time, and radiation dose.

Preoperative computed tomography–guided microcoil localization of small peripheral pulmonary nodules: A prospective randomized controlled trial

Growing, small, peripheral, pulmonary nodules in patients at high risk for lung cancer lead to requests for video-assisted thoracoscopic (VATS) resection for pathologic diagnosis. The purpose of this randomized controlled trial was to determine if preoperative localization using percutaneously placed computed tomography (CT)-guided platinum microcoils decreases the need for thoracotomy or VATS anatomic resection (segmentectomy/lobectomy) for diagnosis. Patients with undiagnosed nodules of 15 mm or less were randomized to either no localization or preoperative microcoil localization. Coils were placed with the distal end deep to the nodule and the superficial end coiled on the visceral pleural surface with subsequent visualization by intraoperative fluoroscopy and VATS.Nodules were removed by VATS wedge excision using endostaplers. The primary outcome was a VATS wedge excision for pathologic diagnosis of the nodule without the need for either thoracotomy or VATS anatomic resection. Sixty patients were randomized and 56 underwent surgery between March 2010 and June 2012. Twenty-nine underwent microcoil localization and 27 did not. The baseline characteristics (age, sex, forced expiratory volume in the first second of expiration, nodule size/depth) were similar. The coil group had a higher rate of successful diagnosis with VATS wedge resection alone (27/29 vs 13/27; P<.001), decreased operative time to nodule excision (37 ± 39 vs 100 ± 67 minutes; P<.001), and reduced stapler firings (3.7 ± 2.0 vs 5.9 ± 31; P=.003) with no difference in total costs. Pathologic diagnoses included 14 benign nodules, 32 primary lung malignancies, and 10 metastases. There were no clinically significant complications related to the coil placement or wedge resection. Preoperative CT-guided microcoil localization decreases the need for thoracotomy or VATS anatomic resection for the diagnosis of small peripheral pulmonary nodules.

Quality of life and outcome after treatment of ruptured cerebral aneurysms: results of a single center in Switzerland.

To evaluate the subjective outcome and quality of life (QoL) of patients who suffered from aneurysmal subarachnoid hemorrhage and underwent endovascular coiling or microsurgical clipping in a single center. For this retrospective single-center study, we included patients who underwent aneurysm occlusion at the Cantonal Hospital of Aarau between January 2000 and December 2006. The QoL, the functional status, and the level of independence were assessed by means of the Short Form (SF)-12 Health Survey, the modified Rankin Scale (mRS), and the Barthel Index. The questionnaires were sent to and completed by the patients. A total of 104 patients with a mean age of 53.14 years (range, 18-80 years) were included in the study. In 63 (60.6 %) of the cases, the aneurysm was clipped; in 41 (39.4 %) of the cases, endovascular coiling was performed. The SF-12 scores for the PCS (Physical Component Summary) and MCS (Mental Component Summary) were similar for both clipped (PCS 45.35; MCS 46.55) and coiled (PCS 46.31; MCS 47.87) patients. The mean values were, on average, 4.17 points lower for the PCS and 2.79 points lower for the MCS when compared with the mean of the US population, with a mean of 50 (standard deviation (SD) 10). The mean Barthel Index for the entire group was 92.26 (SD 16.8) and was almost identical for both the clipped (92.54; SD 16.21) and coiled (91.83; SD 17.9) patients (p = 0.56). The mean mRS did not differ between the coiled and clipped patients (coiled 1.63; clipped 1.56; p = 0.97) CONCLUSIONS: There were no significant differences in the functional and mental health scores between the two groups of clipped and coiled patients who were treated at our center, but both groups were lower than population-based scores. Although the neurologic condition and the imaging results on admission were worse in the coiled group, the long-term results did not differ significantly.

E-037 Single Center Comparison of Ophthalmic Aneurysm Treatment Using Pipeline Embolization Device Versus Coil Embolization

Introduction/purposeAneurysms arising from the ophthalmic segment of the internal carotid artery (ICA) account for approximately 5% of all intracranial aneurysms. The Pipeline Embolization Device (PED) is a relatively new device...

Acceleration of aneurysm healing by P(DLLA-co-TMC)-coated coils enabling the controlled release of vascular endothelial growth factor

Since the introduction of the detachable coil in endovascular treatment of intracranial aneurysms, the in-hospital mortality rate has been significantly decreased. Recurrence of the aneurysm remains the major drawback of using detachable coils. We prepared a bioactive coil coated with poly(d,l-lactide)-7co-(1,3-trimethylene carbonate) (P(DLLA-co-TMC)), a novel copolymer for controlling the release of vascular endothelial growth factor (VEGF). Platinum coils were prepared by successive coating with cationic P(DLLA-co-TMC) and anionic heparin. Then, recombinant human VEGF-165 (rhVEGF) was immobilized by affinity binding to heparin. The morphological characteristics and sustained in vitro release of rhVEGF were examined using scanning electron microscopy and enzyme-linked immunosorbent assay, respectively. The efficacy of these novel coils modified by P(DLLA-co-TMC)/rhVEGF was tested using a common carotid artery aneurysm model in rats. Experimental aneurysms were embolized with unmodified, P(DLLA-co-TMC)/heparin-coated or P(DLLA-co-TMC)/rhVEGF-coated platinum coils (n = 18). The coils were removed on days 15, 30 and 90 after insertion, and the histological and immunohistochemical analysis of factor VIII was performed to confirm the presence of endothelial cells in the organized area. In addition, the controlled in vivo release of VEGF was confirmed by Western blotting analysis. The release of VEGF tended to increase during the whole period and no burst release was observed. In the group treated with P(DLLA-co-TMC)/rhVEGF-coated platinum coils, clot organization and endothelial cell proliferation were accelerated. The immunohistochemistry study showed that the expression of factor VIII was found in the P(DLLA-co-TMC)/rhVEGF-coated coil group but not in the other two groups. Furthermore, Western blotting analysis confirmed that the major released VEGF in the aneurysm sac was from the P(DLLA-co-TMC)/VEGF-coated coil. P(DLLA-co-TMC)/rhVEGF-coated platinum coils can promote clot organization and endothelial cell proliferation in a rat aneurysm model.

Design and Prototype of the High Voltage In-Service-Tests on the Superconducting Magnet System of Wendelstein 7-X

The stresses induced during the energizing and de-energizing process of the Wendelstein 7-X super conducting magnet system could cause cracks in the embedding of the winding packages and consequently a ground fault that would not be detected during normal operation as the operating voltage of the magnet is system is too low. With a ground fault present during a fast discharge, the middle point grounding needed to half the voltage could be rendered useless and one coil group could be stressed with the full voltage of up to 4 kV which would endanger the high voltage integrity of the whole superconducting magnet system. To prevent such undesirable occasions, the insulation of the superconducting magnet system shall be monitored by a high voltage In-Service-Test. With the In-Service-Test, a voltage of 2.5 kV can be applied during the operation of the magnets especially after significant changes in the coil current. The measured leak current can then be used to determine any changes in the quality of the insulation. In a first step, the feasibility of such a system has been evaluated with a simulation model of one coil group with Simplorer. The next step was to find a design which can be implemented in the given magnet power supply system and to build and test a prototype for final confirmation of the concept.

Probabilistic Force Prediction in Cold Sheet Rolling by Bayesian Inference

A primary factor in manufacturing high-quality cold-rolled sheet is the ability to accurately predict the required rolling force. Rolling force directly influences roll-stack deflections, which correlate to strip thickness profile and flatness. Accurate rolling force predictions enable assignment of efficient pass schedules and appropriate flatness actuator set-points, thereby reducing rolling time, improving quality, and reducing scrap. Traditionally, force predictions in cold rolling have employed deterministic, two-dimensional analytical models such as those proposed by Roberts and Bland and Ford. These simplified methods are prone to inaccuracy, however, because of several uncertain, yet influential, model parameters that cannot be established deterministically under diverse cold rolling conditions. Typical uncertain model parameters include the material's strength coefficient, strain-hardening exponent, strain-rate dependency, and the roll-bite friction characteristics at low and high mill speeds. Conventionally, such parameters are evaluated deterministically by comparing force predictions to force measurements and employing a best-fit regression approach. In this work, Bayesian inference is applied to identify posterior probability distributions of the uncertain parameters in rolling force models. The aim is to incorporate Bayesian inference into rolling force prediction for cold rolling mills to create a probabilistic modeling approach that learns as new data are added. The rolling data are based on stainless steel types 301 and 304, rolled on a 10-in. wide, 4-high production cold mill. Force data were collected by observing load-cell measurements at steady rolling speeds for four coils. Several studies are performed in this work to investigate the probabilistic learning capability of the Bayesian inference approach. These include studies to examine learning from repeated rolling passes, from passes of diverse coils, and by assuming uniform prior probabilities when changing materials. It is concluded that the Bayesian updating approach is useful for improving rolling force probability estimates as evidence is introduced in the form of additional rolling data. Evaluation of learning behavior implies that data from sequential groups of coils having similar gauge and material is important for practical implementation of Bayesian updating in cold rolling.

The magnetic field generated by a rotating charged polygon

The magnetic field along the symmetry axis of a regular polygon carrying a uniform electric charge on its edges is calculated systematically when the polygon is rotated about this axis of symmetry. A group of circular current-carrying coils arranged concentrically about the axis of the polygon has been designed to simulate the magnetic field characteristics of the rotating charged polygon. The magnetic field of the simulated coils is measured using the PASCO magnetic field sensor. The results show that the theoretical calculation agrees well with the experimental results.

Coils versus Gelatin Particles with or without Intraarterial Antibiotics for Partial Splenic Embolization: A Comparative Evaluation

PurposeTo compare the efficacy, complications, and inflammatory levels in partial splenic embolization (PSE) with coils or gelatin sponge (GS) particles with or without intraarterial antibiotic agents. Materials and MethodsForty-four patients with hypersplenism treated by PSE were assessed. GS particles were used in 31 patients, and coils were used in 13 patients. In 17 of the 31 patients who received GS, GS suspended in antibiotic solution was injected via the splenic artery. In the other 14 patients, antibiotic agents were not used. In all 13 coil group patients, an antibiotic solution was intraarterially injected before embolization. Platelet counts were compared between the GS and coil groups. Complications and serum C-reactive protein (CRP) levels were compared among the three groups. ResultsThere were no significant differences in platelet counts and platelet increased ratios at 6 months (10.0 × 104/µL and 193% in the GS group vs 9.0 × 104/µL and 221% in the coil group), and no significant differences in frequencies of complications. However, one splenic abscess occurred in a patient treated with GS without antibiotics, resulting in death. The mean serum CRP level in the GS with antibiotic group at 2 weeks was significantly lower than in the other two groups. ConclusionsThe efficacy of PSE is similar with the use of coils versus GS particles. Prophylactic intraarterial antibiotic treatment could be useful in preventing inflammatory reactions after PSE.