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A discrete contact model for complex arbitrary-shaped convex geometries

Particuology 2023年第9期80卷 180-191页

作者： jan e.marquardt Ulrich J.Römer Hermann Nirschl Mathias J.Krause Lattice Boltzmann Research Group Karlsruhe Institute of TechnologyStraße am Forum 8Karlsruhe76131Germany Institute for Mechanical Process engineering and Mechanics Karlsruhe Institute of TechnologyStraße am Forum 8Karlsruhe76131Germany Institute of engineering Mechanics Karlsruhe Institute of TechnologyKaiserstraße 10Karlsruhe76131Germany Institute for Applied and Numerical Mathematics Karlsruhe Institute of TechnologyEnglerstraße 2Karlsruhe76131Germany

The shape of particles has a significant influence on the behavior of suspensions,as the particle-fluid,particle-particle,and particle-wall interactions depend on ***,the simultaneous consideration of complex particle shapes and four-way coupling remains a major *** is mainly due to a lack of suitable contact *** models for complex shapes have been proposed in literature,and most limit the accuracy of the particle-fluid *** this reason,this paper presents a novel contact model for complex convex particle shapes for use with partially saturated methods,in which we propose to obtain necessary contact properties,such as the indentation depth,by a discretization of the contact *** goal of the proposed model is to enable comprehensive and accurate studies of particulate flows,especially with high volume fractions,that lead to new insights and contribute to the improvement of existing industrial *** ensure correctness and sustainability,we validate the model extensively by studying cases with and without *** the latter case,we use the homogenized lattice Boltzmann *** provided investigations show a great agreement of the proposed discrete contact model with analytical solutions and the literature.

关键词： Partially saturated cells method Homogenized lattice Boltzmann method Arbitrarily shaped particle Discrete contact model Particle-resolved simulation OpenLB

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A novel approach to prevent bubble coalescence during measurement of bubble size in flotation

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Journal of Central South University 2014年第1期21卷 338-343页

作者：张炜 jan e.Nesset James A.Finch Mining and Mineral Resources Division Department of Business AdministrationChinalco China Copper Corporation Limited Department of Mining and Materials engineering McGill University

effect of frothers in preventing bubble coalescence during flotation of minerals has long been *** evaluate the performance of a frother,an apparatus to measure the bubble size is a basic *** Bubble Size Analyzer(MBSA) or bubble viewer that has been developed and completed by McGill University's Mineral Processing Group during the last decade is a unique instrument to serve this *** parameters which are thought to influence the bubble size measurements by McGill bubble viewer include water quality and frother concentration in the *** show that there is no difference in Sauter mean(D32) when tap or de-ionized water was used instead of process ***,the frother concentration,in this research DowFroth 250(DF250),inside the chamber exhibited a pronounced effect on bubble *** concentration below a certain point can not prevent coalescence inside the chamber and therefore caution must be taken in plant *** was also noted that the frother concentration which has been so far practiced in plant measurements(CCC75-CCC95) is high enough to prevent coalescence with the bubble viewer.

关键词： flotation frother bubble size bubble coalescence

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Correspondence of bubble size and frother partitioning in flotation

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Journal of Central South University 2014年第6期21卷 2383-2390页

作者：张炜 jan e.Nesset James A.Finch Mining & Mineral Resources Division Department of Business AdministrationChinalco China Copper Corporation Limited Department of Mining and Materials engineering McGill UniversityMontrealQCH3A 0C5Canada

The size of bubbles created in the flotation process is of great importance to the efficiency of the mineral separation ***,it is believed that frother transport between phases is perhaps the most important reason for the interactive nature of the phenomena occurring in the bulk and froth phases in flotation,as frother adsorbed in the surface of rising bubbles is removed from the bulk phase and then released into the froth as a fraction of the bubbles *** causes the increased concentration in the froth compared to the bulk concentration,named as frother *** reflects the adsorption of frother on bubbles and how to influence bubble size is not *** currently exists no such a topic aiming to link these two key *** fill this vacancy,the correspondence between bubble size and frother partitioning was *** size was measured by sampling-for-imaging(SFI)*** total organic carbon(TOC)analysis to measure the frother partitioning between froth and bulk phases was *** have shown,with no exceptions including four different frothers,higher frother concentration is in the bulk than in the *** results also show strong partitioning giving an increase in bubble size which implies there is a compelling relationship between these two,represented by CFroth/CBulk and *** CFroth/CBulkand D32 curves show similar exponential decay relationships as a function of added frother in the system,strongly suggesting that the frother concentration gradient between the bulk solution and the bubble interface is the driving force contributing to bubble size reduction.

关键词： flotation frother bubble size frother partitioning total organic carbon (TOC) analysis concentration gradient

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Bubble size as a function of some situational variables in mechanical flotation machines

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Journal of Central South University 2014年第2期21卷 720-727页

The specific results of the work investigating the effect of gas density and water temperature on bubble size were *** were surrogate variables designed to investigate the effect of viscosity(varying water temperature) and altitude(varying gas density).The results show that there is a measurable but relatively small effect of gas density on bubble *** D32 is revealed to increase proportionally as(ρ0/ρg)*** projected impact on flotation kinetics at 4500 m versus sea level is small,of the order of 0.5% recovery loss for a bank of eight flotation *** effect of water temperature(4-40 °C) on bubble size is more significant than gas *** relationship correlates with water viscosity values quite closely.A finding that D32 increases proportionally as(μ/μ20)0.776 highlights the importance of accounting for viscosity effects if,for example,large process temperature fluctuations or deviation from design/test conditions are expected.

关键词： flotation frother bubble size viscosity altitude

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Quantitative evaluation of the results of digital forensic investigations:a review of progress

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Forensic Sciences Research 2021年第1期6卷 13-18页

作者： Richard e.Overill jan Collie Department of Informatics King’s College LondonLondonUK Department of Computing&Communication The Open UniversityMilton KeynesUK

Unlike conventional forensics,digital forensics does not at present generally quantify the results of its *** is suggested that digital forensics should aim to catch up with other forensic disciplines by using Bayesian and other numerical methodologies to quantify its investigations’*** the plausibility of alternative hypotheses(or propositions,or claims)which explain how recovered digital evidence came to exist on a device could assist both the prosecution and the defence sides in criminal proceedings:helping the prosecution to decide whether to proceed to trial and helping defence lawyers to advise a defendant how to *** paper reviews some numerical approaches to the goal of quantifying the relative weights of individual items of digital evidence and the plausibility of hypotheses based on that *** potential advantages enabling the construction of cost-effective digital forensic triage schemas are also outlined.

关键词： Forensic sciences digital forensic metrics measures of plausibility Bayesian networks probability theory statistical theory complexity theory information theory

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effects of cereal fiber on bowel function: A systematic review of intervention trials

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World Journal of Gastroenterology 2015年第29期21卷 8952-8963页

作者： jan de Vries Paige e Miller Kristin Verbeke De Vries Nutrition Solutions Inc. Center for epidemiology Biostatistics and Computational Biology Exponent Inc. Nutrition and Food Service Edward Hines Jr. VA Hospital Hines Department of Clinical and experimental Medicine KU Leuven

AIM: To comprehensively review and quantitatively summarize results from intervention studies that examined the effects of intact cereal dietary fiber on parameters of bowel function. MeTHODS: A systematic literature search was conducted using Pub Med and eMBASe. Supplementary literature searches included screening reference lists from relevant studies and reviews. eligible outcomes were stool wet and dry weight, percentage water in stools, stool frequency and consistency, and total transit time. Weighted regression analyses generated mean change(± SD) in these measures per g/d of dietary fiber. ReSULTS: Sixty-five intervention studies among generally healthy populations were identified. A quantitative examination of the effects of non-wheat sources of intact cereal dietary fibers was not possible due to an insufficient number of studies. Weighted regression analyses demonstrated that each extra g/d of wheat fiber increased total stool weight by 3.7 ± 0.09 g/d(P eight by 0.75 ± 0.03 g/d(P equency by 0.004 ± 0.002 times/d(P = 0.0346; 95%CI: 0.0003-0.0078). Transittime decreased by 0.78 ± 0.13 h per additional g/d(P eat fiber among those with an initial transit time greater than 48 ***: Wheat dietary fiber, and predominately wheat bran dietary fiber, improves measures of bowel function.

关键词： Comprehensive review Dietary fiber Wheat bran Cereal Bowel function

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Stable ischemic heart disease in the older adults

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Journal of Geriatric Cardiology 2016年第2期13卷 109-114页

作者： Xuming DAI jan Busby-Whitehead Daniel e Forman Karen P Alexander Division of Cardiology University of North Carolina at Chapel Hill Chapel Hill North Carolina USA Division of Geriatric Medicine Center for Aging and Health University of North Carolina at Chapel Hill North Carolina USA Section of Geriatric Cardiology University of Pittsburgh Medical Center Geriatrics Research Education and Clinical Center VA Pittsburgh Healthcare System Pittsburgh PA USA Division of Cardiology Duke University Medical Center Durham North Carolina USA

1 Introduction Ischemic heart disease is caused by atherosclerotic and/or thrombotic obstruction of coronary arteries. Clinical spec- trum of ischemic heart disease expands from asymptomatic atherosclerosis of coronary arteries to acute coronary syn- dromes （ACS） including unstable angina, acute myocardial infarction （non-ST elevation myocardial infarction and ST elevation myocardial infarction）. Stable ischemic heart dis- ease （SIHD） refers to patients with known or suspected SIHD who have no recent or acute changes in their symp- tomatic status, suggesting no active thrombotic process is underway.

关键词： Aging Coronary artery disease Older adults Risk assessment Stable ischemic heart disease

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The effect of Tyrophagus putrescentiae on Fusarium poae transmission and fungal community in stored barley in a laboratory experiment

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Insect Science 2014年第1期21卷 65-73页

作者： jan Hubert Marta Nesvorna jan Kopecky Crop Research Institute Praha 6 Czech Repubfic

The effect of Tyrophagus putrescentiae on Fusarium poae transmission and fungal community composition was studied in nonsterile barley grain. The experiments included following treatments： control barley without mites; barley containing l0 or 50 mites without preincubation on e poae （Tpl0 and TpS0）; barley containing 10 or 50 mites after preincubation on e poae （FTp 10 and FTp50）. The number of mites, suc cessful transfer of e poae, and changes in the fungal communities were examined after 21 d of experiment. Increase of deoxynivalenol （DON） content in the barley was chosen as a criterion of successful epoae transfer. The preincubation of T. putrescentiae on epoae increased DON level approximately to 800 and 300μg/kg of grain for FTpl0 and FTpS0, respectively. T. putrescentiae population growth in FTpl0 was lower than in Tpl0, while no difference was found between FTp50 and Tp50. Fungal communities were compared by amplification, cloning and sequencing of ITS fragments, and operational taxonomic units （OTU） analysis. The OTU analysis did not support the transfer ofF. poae via mites. From the analyzed clones, only 13 cloned sequences clustered with e poae in an OTU defined at distance level 0.07. The related clones originated from FTpl0, Tpl 0, Tp50 and control treatments, but not from FTp50. However, the presence of e poae in FTp50 was confirmed by PCR amplification with specific primers. The observation may be explained by different effect of mite population density, that is, in the high density, （FTp50 treatment） the fungus was overgrazed, while the lower population density （FTp 10） supported e poae transfer.

关键词： barley deoxinivalenol (DON) Fusariumpoae mites mycotoxin storage

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exercise-based real-time telerehabilitation for older patients recently discharged after transcatheter aortic valve implantation: An extended feasibility study

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Journal of Geriatric Cardiology 2023年第11期20卷 767-778页

作者： Barbara Cristina Brocki jan Jesper Andreasen Jens Aarøe jane Andreasen Charlotte B Thorup Department of Physiotherapy and Occupational Therapy Aalborg University HospitalDenmark Department of Cardiothoracic Surgery Aalborg University Hospital and Clinical InstituteAalborg UniversityDenmark Department of Cardiology Aalborg University HospitalDenmark Public Health and epidemiology Group HealthScience and TechnologyAalborg UniversityDenmark Research Center of Health and Applied Technology University College Northern DenmarkDenmark

OBJeCTIVeS To assess the extended feasibility of a telerehabilitation program and its effects on physical performance in older adults who have recently undergone transcatheter aortic valve implantation(TAVI).MeTHODS In this single-center feasibility study, patients underwent an eight-week telerehabilitation program, involving webbased home exercise training twice weekly, an activity tracker, access to an informative website, and one online session with a nurse, starting one-week postoperative. Data collection was performed before surgery and three months postoperative. The feasibility of the intervention was based on recruitment and adherence to the program. As a secondary outcome, we evaluated the change in six-minute walk distance from before surgery to three months *** Forty-one patients scheduled for TAVI were assessed for eligibility;15 patients(37%) were enrolled. Of these, eight were excluded after surgery due to tiredness(n = 2), non-cardiac related hospital readmission(n = 2), fluctuating health(n = 1),death during hospital stay(n = 1), and reduced cognition(n = 2). Seven patients completed the eight-week web-based intervention and were evaluated three months postoperative. Their median(IQR) age was 83 [81, 87] years, and the sample comprised three men and four women. Their walked distance improved from median(IQR) 262 [199, 463] before surgery, to 381 [267, 521]meters three months postoperative. No adverse events were *** Web-based telerehabilitation, including supervised exercise training, in older adults who have recently undergone TAVI was feasible for a small number of patients who completed the eight-week intervention. This was reflected in an improvement in their walked distance three months after the surgery. However, the low recruitment and retention rates do question the overall feasibility of this intervention in a frail, older population of post-TAVI patients.

关键词： patients nurse implantation

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A Comparison of experimental and Numerical Studies Performed on a Low-Pressure Turbine Blade Cascade at High-Speed Conditions, Low Reynolds Numbers and Various Turbulence Intensities

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Journal of Thermal Science 2013年第5期22卷 413-423页

作者： jan Michalek Petr Straka VZLU - Aerospace Research and Test establishment Beranovych 130 19500 PragueCzech Republic

This paper focuses on a comparison of experimental and numerical investigations performed on a low-pressure mid-loaded turbine blade at operating conditions comprised of a wide range of Math numbers （from 0.5 - 1.1）, Reynolds numbers （from 0.4e＋5 - 3.0e＋5）, flow incidence （-15 - 15 degrees） and three levels of free-stream tur- bulence intensities （2, 5 and 10%）. The experimental part of the work was performed in a high-speed linear cas- cade wind tunnel. The increased levels of turbulence were achieved by a passive grid placed at the cascade inlet. A two-dimensional flow field at the center of the blade was traversed pitch-wise upstream and downstream the cascade by means of a five-bole probe and a needle pressure probe, respectively. The blade loading was measured using the surface pressure taps evenly deployed at the blade mid-span along the suction and the pressure side. The inlet turbulence was investigated using the constant temperature anemometer technique with a dual sensor probe. experimentally evaluated values of turbulent kinetic energy and its dissipation rate were then used as inputs for the numerical simulations. An in-house code based on a system of the Favre-averaged Navier-Stokes equation closed by a two-equation k-co turbulence model was adopted for the predictions. The code utilizes an algebraic model of bypass transition valid both for attached as for separated flows taking in account the effect of free-stream turbulence and pressure gradient. The resulting comparison was carried out in terms of the kinetic en- ergy loss coefficient, distributions of downstream wakes and blade velocity. Additionally a flow visualization was performed by means of the Schlieren technique in order to provide a further understanding of the studied phe- nomena. A few selected cases with a particular interest in the attached and separated flow transition are compared and discussed.

关键词： low pressure turbine high-speed flow low Reynolds number flow separation transition RANS

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