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Novel and Simple Calorimetric Methods for Quantifying Losses in Magnetic Core and GaN Transistor in a High Frequency Boost Converter

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Chinese Journal of Electrical Engineering 2016年第2期2卷 68-75页

作者： Wenbo Wang Frans Pansier sjoerd de Haan J.A.Ferreira DCE&S Faculty of Electrical EngineeringMathematics and Computer ScienceDelft University of TechnologyDelftThe Netherlands

In design and implementation of a boost converter,information on loss characteristics of switching devices and magnetic materials is a prerequisite,especially in high frequency *** gather such information,testing and accurate loss quantification is *** methods for measuring magnetic core loss are either only suitable for sinusoidal wave excitations or cannot separate winding loss from inductor *** addition,existing loss measurement approaches on the newly introduced GaN transistors are not *** this paper,we present a new method to distinguish winding loss from inductor loss under practical *** method utilizes a converter to generate the actual excitation waveforms and uses a calorimetric setup to quantify the *** splitting up the inductor in a converter into an air-core inductor and a magnetic-core inductor,both equipped with exactly the same winding structure,the air-core inductor loss can be used as the reference of the magnetic-core inductor winding *** this way,losses in the magnetic core can be determined in the actual operating condition of a converter in which the inductor is to be ***,a simple calorimetric approach for obtaining loss information of GaN transistors are is also *** methods require simple setup and are easy and convenient to *** methods work well in assessing different high frequency magnetic core materials and measuring losses in GaN transistors at 1MHz.

关键词： Core loss measurement practical excitation high frequency magnetic material practical excitation transistor loss measurement calorimetric method

Effect of viscosity on the avalanche dynamics and flow transition of wet granular matter

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Particuology 2021年第6期19卷 64-75页

作者： Jens H.Kasper Vanessa Magnanimo sjoerd D.M.de Jong Arjan Beek Ahmed Jarray Multi-Scale Mechanics(MSM) Thermal and Fluid EngineeringFaculty of Engineering Technology.University ofTwenteP.O.Box 2177500 AE EnschedeThe Netherlands Construction Management and Engineering(CME) Faculty of Engineering TechnologyUniversity ofTwenteP.O.Box 2177500 AE EnschedeThe Netherlands

The dynamic behaviour of granular flows is important in geo-mechanics and industrial applications,yet poorly *** studied the effects of liquid viscosity and particle size on the dynamics of wet granular material flowing in a slowly rotating drum,in order to detect the transition from the avalanching to the continuous flow regime.A discrete element method(DEM)model,in which contact forces and cohesive forces were considered,was employed to simulate this flow *** model was validated experimentally,using glass beads in a wooden drum and water–glycerol mixtures to tune the liquid *** DEM simulations showed comparable results to the experiments in terms of average slope angle and avalanche *** observed that the avalanche amplitude,flow layer velocity and granular temperature decrease as the liquid viscosity *** effect is more pronounced for smaller sized *** increase in viscous forces causes the flowing particles to behave as a bulk,pushing the free surface towards a convex *** addition,avalanches become less pronounced and the granular flow transitions from the avalanching regime to the continuous *** avalanching flow regime is marked by intermittent rigid body movement of the particulate bed and near-zero drops in the granular temperature,while no rigid body movement of the bed occurs in the continuous flow *** identified the avalanching-continuous flow transition region as a function of a dimensionless granular Galileo number.

关键词： Granular avalanche Transition Cohesion Viscosity Rotary drum DEM

Bowel intussusception caused by a percutaneously placed endoscopic gastrojejunostomy catheter: A case report

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World Journal of Gastrointestinal Surgery 2022年第6期14卷 621-625页

作者： Maarten WJ Winters sjoerd Kramer Albert HA Mazairac Ewoud H Jutte Paul G van Putten Department of Gastroenterology and Hepatology Medical Center LeeuwardenLeeuwarden 8934 ADNetherlands Department of Radiology Medical Center LeeuwardenLeeuwarden 8934 ADNetherlands Department of Surgery Medical Center LeeuwardenLeeuwarden 8934 ADNetherlands

BACKGROUND In adults,bowel intussusception is a rare diagnosis and is mostly due to an organic bowel *** rare cases,this is a complication of a percutaneously placed endoscopic gastro(jejunostomy)*** SUMMARY We describe a case of a 73-year-old patient with a history of myocardial infarction,chronic idiopathic constipation and Parkinson’s *** the admission of his Parkinson’s medication,a percutaneous endoscopic gastrostomy with jejunal extension(PEG-J)was *** patient presented three times at the emergency department of the hospital with intermittent abdominal pain with nausea and *** were no distinctive abnormalities from the physical and laboratory *** abdominal computed tomography scan showed a small bowel *** push endoscopy,a jejunal bezoar at the tip of the PEG-J catheter was found to be the cause of small bowel *** intussusception was resolved after removing the bezoar during push *** Endoscopic treatment of bowel intussusception caused by PEG-J catheter bezoar.

关键词： Bowel intussusception Percutaneous endoscopic gastrojejunostomy Bezoar Percutaneous endoscopic gastrostomy Case report

Clinical efficacy of the Ankle Spacer for the treatment of multiple secondary osteochondral lesions of the talus

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World Journal of Orthopedics 2022年第2期13卷 178-192页

作者： Jari Dahmen J Nienke Altink Gwendolyn Vuurberg Coen A Wijdicks sjoerd AS Stufkens Gino MMJ Kerkhoffs Department of Orthopedic Surgery Amsterdam UMCLocation AMCAmsterdam 1105AZNetherlands Department of Orthopedic Research ArthrexNaplesFL 34108United States

BACKGROUND The Ankle Spacer was developed as a joint-sparing alternative to invasive endstage ***,there are no clinical studies on the Ankle *** To describe the operative technique and the clinical efficacy of the Ankle Spacer for the treatment of multiple,cystic osteochondral lesions of the talus in patients with failed prior operative *** This is a prospective study during which patients were assessed preoperatively,at 2-and 6 wk,and at 3,6,12 and 24 mo *** with multiple,cystic or large(≥15 mm)osteochondral lesions of the talus after failed prior surgery were *** primary outcome measure was the numeric rating scale(NRS)for pain during walking at 2 years *** outcome measures included the NRS in rest and during stair climbing,the American Orthopaedic Foot and Ankle Society Hindfoot Score,the Foot and Ankle Outcome Score,the Short-Form 36 physical and mental component scale,and the Range of Motion(ROM).Radiographic evaluations were conducted to evaluate prosthetic loosening and *** rates and complications were also *** Two patients underwent an Ankle Spacer implantation on the *** NRS during walking improved from 6 and 7 preoperatively to 2 and 2 points postoperatively at 2 years,in patient 1 and 2,*** other patient-reported outcome measures also improved *** were no re-operations nor *** imaging showed no loosening of the implant and no change of implant *** The Ankle Spacer showed clinically relevant pain reduction during walking,improvement in clinical outcomes as assessed with PROMs,and no complications or *** treatment option may evolve as a joint-sparing alternative to invasive end-stage surgeries.

关键词： Hemi-arthroplasty Ankle Spacer Talar surface implant Osteochondral lesions of the talus Endstage

Can bedside needle arthroscopy of the ankle be an accurate option for intra-articular delivery of injectable agents?

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World Journal of Orthopedics 2022年第1期13卷 78-86页

作者： Tobias Stornebrink sjoerd A S Stufkens Nathaniel P Mercer John G Kennedy Gino M M J Kerkhoffs Department of Orthopedic Surgery Amsterdam UMCUniversity of AmsterdamAmsterdam Movement SciencesAmsterdam 1105AZNetherlands Academic Center for Evidence based Sports Medicine Amsterdam 1105AZNetherlands Amsterdam Collaboration for Health and Safety in Sports International Olympic Committee Research Center Amsterdam UMCAmsterdam 1105AZNetherlands Department of Orthopedic Surgery NYU Langone HealthNew YorkNY 10010United States

BACKGROUND Bedside needle arthroscopy of the ankle under local anesthesia has been proposed for intra-articular delivery of injectable *** and tolerability of this approach in the clinical setting–including patients with end-stage ankle pathology and/or a history of prior surgery–is not *** To assess clinical accuracy and tolerability of bedside needle arthroscopy as a delivery system for injectable agents into the tibiotalar *** This was a prospective study that included adult patients who were scheduled for an injection with hyaluronic acid to the tibiotalar *** our center,these injections are used as a last resort prior to extensive *** primary outcome was injection accuracy,which was defined as injecting through the arthroscopic cannula with intra-articular positioning confirmed by a clear arthroscopic view of the joint *** outcome measures included a patientreported numeric rating scale(NRS,0-10)of pain during the procedure and willingness of patients to return for the same *** of ankle pain at rest and during walking was collected at baseline and at 2-wk *** were monitored from inclusion up to a 2-wk control *** We performed 24 ***(46%)participants were male,and mean age was 46.8±14.5 *** was the indication for injection in 20(83%)cases,of which 8(33%)patients suffered from osteoarthritis Kellgren-Lawrence grade IV,and 10(42%)patients from Kellgren-Lawrence grade *** osteochondral defect was the indication for injection in 4(17%)cases.A history of ankle surgery was present in 14(58%)participants and a history of multiple ankle surgeries in 11(46%)*** was possible to confirm accuracy in 21(88%)*** 3(12%)participants where needle arthroscopy did not reach a clear view of the joint space all suffered from Kellgren-Lawrence grade IV *** during the procedure was reported with a median of 1[i

关键词： Ankle arthroscopy NanoScope Needle arthroscopy Injections Proof of concept Patient experience

Mid-term survival of the Optimys short stem: A prospective case series of 500 patients

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World Journal of Orthopedics 2024年第3期15卷 257-265页

作者： Bryan Hamans Sheryl de Waard sjoerd Kaarsemaker Esther R C Janssen Inger N Sierevelt Gino M M J Kerkhoffs Daniël Haverkamp Department of Orthopaedic Surgery Xpert ClinicAmsterdam 1101EANetherlands Department of Orthopedic Surgery Amsterdam University Medical CenterAmsterdam 1105 AZNetherlands Esther R C Janssen Department of Orthopaedic SurgeryViecuri Medisch CentrumVenlo 5912 BLNetherlands Centre for Orthopaedic Research Spaarne ZiekenhuisHoofddorp 2134 TMNetherlands Department of Orthopaedic Surgery and Sports Medicine Amsterdam UMC-Location AMCAmsterdam 1105 AZNetherlands Department of Orthopedic Surgery Xpert Orthopedic Surgery ClinicAmsterdam 1101 EANetherlands

BACKGROUND In recent years,there has been an increase in the number of total hip arthroplasty procedures in the younger patient *** active group has higher expectations of their prosthesis in comparison to the older population,and there is a greater physical demand for the *** femoral stems were in-troduced to retain proximal bone stock and joint biomechanics and became more common to implant in this specific ***,the long-term survival and functional outcomes of various short stems are still being investigated in different *** To determine the 5-year survival of the Optimys hip *** This was a prospective multicenter cohort study of 500 patients conducted in two hospitals in the *** patients received the Optimys short stem(Mathys Ltd,Bettlach,Switzerland).The primary outcome measure was survival of the hip stem,with revision as the *** secondary outcome measurements included patient-reported outcome measures(PROMs).Kaplan-Meier analysis was used to calculate the 5-year survival ***-minus-log transformation was performed to calculate the 95%confidence interval(95%CI).Mixed model analyses were performed to assess the course of the PROMs during the 1st 2 years after *** were modeled separately for the 1st and 2nd years to calculate the yearly change in PROMs during both follow-up periods with accompanying 95%*** The mean age of the total 500 patients was 62.3 years(standard deviation:10.6)and 202 were male(40%).At a median follow-up of 5.5 years(interquartile range:4.5-6.7),7 patients were deceased and 6 revisions were registered,for infection(n=3),subsidence(n=2)and malposition(n=1).This resulted in an overall 5-year survival of 98.8%(95%CI:97.3-99.5).If infection was left out as reason for revision,a stem survival of 99.4%(95%CI:98.1-99.8)was *** questionnaires were completed by 471 patients(94%),317 patients(63%)completed the 1-year follow-up questionna

关键词： Total hip arthroplasty Femoral stem Short stem Optimys Survival 5-year survival Revision PROMs

Terahertz Generation Using Implanted InGaAs Photomixers and Multi-wavelength Quantum Dot Lasers

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Nano-Micro Letters 2012年第1期4卷 10-13页

作者： Y.Hou J.R.Liu M.Buchanan A.J.Spring Thorpe P.J.Poole H.C.Liu Ke Wu sjoerd Roorda X.P.Zhang Institute for Microstructural Sciences National Research Council Also with Department of Electrical Engineering Concordia University Now with Key Laboratory of Artificial Structures and Quantum Control Department of Physics Shanghai Jiao Tong University Department of Electrical Engineering Ecole Polytechnique Département de physique Université de Montréal Department of Electrical Engineering Concordia University

We report on a study of terahertz(THz) generation using implanted In Ga As photomixers and multi-wavelength quantum dot lasers. We carry out In Ga As materials growth, optical characterization, device design and fabrication, and photomixing experiments. This approach is capable of generating a comb of electromagnetic radiation from microwave to terahertz. For shortening photomixer carrier lifetime, we employ proton implantation into an epitaxial layer of lattice matched In Ga As grown on InP. Under a 1.55 μm multimode In GaAs/In GaAsP quantum dot laser excitation, a frequency comb with a constant frequency spacing of 50 GHz generated on the photomixer is measured, which corresponds to the beats of the laser longitudinal modes. The measurement is performed with a Fourier transform infrared spectrometer. This approach affords a convenient method to achieve a broadband multi-peak coherent THz source.

关键词： Proton implanted In Ga As Trahertz Photomixer Multi-wavelength quantum dot laser Fourier transform infrared spectroscopy

Metabolic-associated Fatty Liver Disease as Assessed by the Fatty Liver Index Among Migrant and Non-migrant Ghanaian Populations

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Journal of Clinical and Translational Hepatology 2021年第4期9卷 494-502页

作者： Anne-Marieke van Dijk sjoerd Dingerink Felix Patience Chilunga Karlijn Anna Catharina Meeks Silver Bahendeka Matthias Bernd Schulze Ina Danquah Tracy Bonsu Osei Erik Serné Charles Agyemang Adriaan Georgius Holleboom Department of Vascular Medicine Amsterdam UMClocation AMCAmsterdamthe Netherlands Department of Public Health Amsterdam UMClocation AMCAmsterdam Public Health Research InstituteAmsterdamthe Netherlands Center for Research on Genomics and Global Health National Human Genome Research InstituteNational Institutes of HealthBethesdaMDUSA MKPGMS-Uganda Martyrs University KampalaUganda Department of Molecular Epidemiology German Institute of Human Nutrition Potsdam-RehbrueckeNuthetalGermany Institute of Nutritional Science University of PotsdamNuthetalGermany Heidelberg Institute of Global Health(HIGH) Universitaetsklinikum HeidelbergHeidelbergGermany Department of Vascular Medicine Amsterdam UMClocation VUmcthe Netherlands

Background and Aims:Metabolic-associated fatty liver disease(MAFLD)is driven by high caloric intake and sedentary *** towards high income countries may induce these driving factors;yet,the influence of such on the prevalence of MAFLD is clearly ***,we investigated the Fatty Liver Index(FLI),a proxy of steatosis in MAFLD,after migration of Ghanaian ***:Cross-sectional data of 5282 rural,urban and migrant participants from the Research on Obesity and Diabetes among African Migrants(also known as RODAM)study were analyzed with logistic regression for geographical differences in FLI and associations with type 2 diabetes mellitus(T2DM),waist-to-hip ratio,and 10-year predicted risk of atherosclerotic cardiovascular disease(ASCVD).Results:Both FLI and the proportion with an FLI indicative of MAFLD steatosis(FLI≥60)were higher in migrants compared with *** of elevated FLI(FLI≥60)in non-migrant males was 4.2%compared to 28.9%in *** females,a similar gradient was observed,from 13.6%to 36.6%*** to rural residents,the odds for a FLI≥60 were higher in migrants living in urban Europe(odds ratio[OR]9.02,95%confidence interval[CI]:5.02–16.20 for men,and 4.00,95%CI:3.00–5.34 for women).Compared to controls,the ORs for FLI≥60 were 2.43(95%CI:1.73–3.41)for male T2DM cases and 2.02(95%CI:1.52–2.69)for female T2DM ***-unit higher FLI was associated with an elevated(≥7.5%)10-year ASCVD risk(OR:1.051,95%CI:1.041–1.062 for men,and 1.020,95%CI:1.015–1.026 for women).Conclusions:FLI as a proxy for MAFLD increased stepwise in Ghanaians from rural areas,through urban areas,to *** results clearly warrant awareness for MAFLD in migrant population as well as confirmation with imaging modalities.

关键词： Fatty liver Non-invasive test Migration African population

3D printing of patient-specific neck splints for the treatment of post-burn neck contractures

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Burns & Trauma 2018年第2期6卷 155-157页

作者： Dafydd O.Visscher sjoerd te Slaa Marielle E.Jaspers Marloes van de Hulsbeek Jorien Borst Jan Wolff Tymour Forouzanfar Paul P.van Zuijlen Department of Plastic Reconstructive and Hand SurgeryAmsterdam Movement SciencesVU University Medical Centerde Boelelaan 11171081HV Amsterdamthe Netherlands 3D InnovationLab VU University Medical CenterAmsterdamthe Netherlands Department of Oral and Maxillofacial Surgery/Oral Pathology VU University Medical CenterAmsterdamthe Netherlands Department of Medical Technology VU University Medical CenterAmsterdamthe Netherlands Department of Plastic Reconstructive and Hand Surgery/Burn CenterRed Cross HospitalBeverwijkthe Netherlands Department of Occupational Therapy Red Cross HospitalBeverwijkthe Netherlands.

Dear Editor,Burn scar contracture is a common problem in healing burn wounds of the neck. It can cause both pain and dysfunction if not treated adequately (1)The treatment of such wounds often involves a combination of surgery and splinting therapy (2)A variety of splints, including the thermoplastic static neck splint [3], the Watusi collar [4], manually fabricated splints, and pre-fabricated splints such as the Philadelphia collar have been used for the management of scar contractures. However, each type of splint has its own advantages and disadvantages, and none of these splints seem to reduce the need for skin reconstruction nor delays the time until surgical re-construction [5].

关键词： Neck burns Contracture 3D printing Neck splint Clinical Optical 3D scanning