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Predicting the mode of flow in pneumatic conveying systems—A review

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Particuology 2008年第5期6卷 289-300页

作者： mark G.Jones Kenneth C.williams Centre for Bulk Solids and Particulate Technologies School of EngineeringUniversity of NewcastleNewcastle 2308Australia

An initial prediction of the particulate mode of flow in pneumatic conveying systems is beneficial as this knowledge can provide clearer direction to the pneumatic conveying design process. There are three general categories of modes of flow, two dense flows： fluidised dense phase and plug flow, and dilute phase oniy. Detailed in this paper is a review of the commonly used and available techniques for predicting mode of flow. Two types of predictive charts were defined： basic particle parameter based （e.g. particle size and density） and air-particle parameter based （e.g. permeability and de-aeration）. The basic particle techniques were found to have strong and weak areas of predictive ability, on the basis of a comparison with data from materials with known mode of flow capability. It was found that there was only slight improvement in predictive ability when the particle density was replaced by loose-poured bulk density in the basic parameter techniques. The air-particle-parameter-based techniques also showed well-defined regions for mode of flow prediction though the data set used was smaller than that for the basic techniques. Also, it was found to be difficult to utilise de-aeration values from different researchers and subsequently, an air-particle-based technique was developed which does not require any de-aeration parameter in its assessment.

关键词： Pneumatic conveying Mode of flow Dense phase Permeability De-aeration

Determination of slug permeability factor for pressure drop prediction of slug flow pneumatic conveying

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Particuology 2008年第5期6卷 307-315页

作者： Kenneth C.williams mark G.Jones Tobias Krull Centre for Bulk Solids and Particulate Technology The University of NewcastleCallaghanNSW 2308Australia

Current models for pressure drop prediction of slug flow pneumatic conveying in a horizontal pipeline system assume some type of steady state conditions for prediction, which limits their capability for increased predictive accuracy relative to experimental data. This is partly because of the nature of slug flow pneumatic conveying system, which, as a dynamic system, never becomes stable. By utilising conservation of mass （airflow）, a dynamic pressure analysis model is proposed on the basis of the derivative of the upstream pressure behaviour. The rate of air permeation through slug, one of the important factors in the conservation model, is expressed as a function of a slug permeability factor. Other factors such as slug velocity, slug length and the fraction of stationary layer were also considered. Several test materials were conveyed in single-slug tests to verify the proposed pressure drop model, showing good agreement between the model and experimental results.

关键词： Slug flow pneumatic conveying Pressure drop Air mass conversation Slug permeability factor

A Survey of Language-Based Approaches to Cyber-Physical and Embedded System Development

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Tsinghua Science and Technology 2015年第2期20卷 130-141页

作者： Paul Soulier Depeng Li john R. williams University of Hawaii Massachusetts Institute of Technology(MIT)

As computers continue to advance, they are becoming more capable of sensing, interacting, and communicating with the physical and cyber world. Medical devices, electronic braking systems in automotive applications, and industrial control systems are examples of the many Cyber-Physical Systems （CPS） that utilize these computing capabilities. Given the potential consequences of software related failures in such systems, a high degree of safety, security, and reliability is often required. Programming languages are important tools used by programmers to develop CPS. They provide a programmer with the ability to transform designs into machine code. Of equal importance is their ability to detect and avoid programming mistakes. The development of CPS has predominantly been accomplished using the C programming language. Although C is a powerful language, it lacks features present in other languages that facilitate the development of reliable systems. This has prompted research into language-based alternatives for improving program quality through the use of programming languages. This paper presents an overview of the characteristics of embedded and cyber-physical systems and the associated requirements imposed on programming languages. This is followed by a survey of relevant research into language- based methods for creating safe, reliable, and robust software for CPS.

关键词： cyber-physical systems embedded systems programming languages type systems

Characterization of the gas pulse frequency,amplitude and velocity in non-steady dense phase pneumatic conveying of powders

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Particuology 2008年第5期6卷 301-306页

作者： Kenneth C.williams mark G.Jones Ahmed A.Cenna Centre for Bulk Solids and Particulate Technologies School of EngineeringUniversity of Newcastle

Current modelling techniques for the prediction of conveying line pressure drop in low velocity dense phase pneumatic conveying are largely based on steady state analyses. Work in this area has been on-going for many years with only marginal improvements in the accuracy of prediction being achieved. Experimental and theoretical investigations undertaken by the authors suggest that the flow mechanisms involved in dense phase conveying are dominated by transient effects rather than those of steady state and are possibly the principal reasons for the limited improvement in accuracy. This paper reports on investigations on the pressure fluctuation behaviour in dense phase pneumatic conveying of powders. The pressure behaviour of the gas flow in the top section of the pipeline was found to exhibit pulsatile oscillations. In particular, the pulse velocity showed variation in magnitude while the frequency of the oscillations rarely exceeded 5 Hz. A wavelet analysis using the Daubechie 4 wavelet found that the amplitude of the oscillations increased along the pipeline. Furthermore, there was significant variation in gas pulse amplitude for different types of particulate material.

关键词： Pneumatic conveying Powders Dense phase Pulsatile flow Transient flow

A Couple Nagging Interpretive Difficulties in Zhuangzi Studies vis-à-vis William James on the Ethics and Psychology of Belief

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Frontiers of Philosophy in China 2019年第4期14卷 593-611页

作者： john Robert williams Department of Philosophy National University of SingaporeSingapore 117570Singapore

The present article addresses two lingering questions in the interpretation of the Zhuangzi莊子—(a)How can one reconcile the scepticism of the Zhuangzi with its positive project(s)?and(b)Who can become a sagely person?The questions are addressed with reference to aspects of William James’accounts of the ethics and psychology of belief.

关键词： Zhuangzi William James scepticism ethics of belief psychology of belief sagely person

A qualitative study on the pulsatile flow phenomenon in a dense fly ash pneumatic conveyor

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Particuology 2014年第6期12卷 81-91页

作者： Wei Chen Kenneth C.williams Isabel Jabs mark G.Jones Centre for Bulk Solids and Particulate Technologies Newcastle Institute for Energy and ResourcesThe University of Newcastle Faculty of Mechanical Engineering Leibniz University of Hanover

Understanding of the dynamic particulate flow structures within a dense gas-fly ash pneumatic conveyor must be improved in order to better aid its design *** complex pulsatile movement of the gas-fly ash mixture dominates the flow performance within the pipeline,and historically,non-invasive measurement devices such as the electrical capacitance tomography（ECT） were often used to sufficiently capture the flow ***,inadequate studies have been conducted on the pulsatile flow phenomenon,which directly relate to the gas-fly ash two-phase flow *** paper aims to investigate the pulsatile flows using an ECT ***,pulsatile flow patterns under various experimental conditions were obtained through *** within a flow were then characterised into pulse growth and decay segments,which represent the superficial fluidisation and deaeration processes during ***,structural and statistical analyses were performed on the pulse growth and decay *** suggested that the increasing air mass flow rate led to the decrease of the superficial fluidisation/deaeration magnitude,however,the increase of the superficial fluidisation/deaeration ***,the air mass flow rate was indicated as the dominant factor in determining the pulsing statistical *** research provides fundamental insights for further modelling the dense fly ash pneumatic flows.

关键词： Pneumatic conveying Electrical capacitance tomography Fly ash Pulsatile flows Flow pattern analysis

Can a Purposeful Walk Intervention with a Distance Goal Using an Activity Monitor Improve Individuals'Daily Activity and Function Post Total Hip Replacement Surgery.A Randomized Pilot Trial

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Cyborg and Bionic Systems 2023年第1期4卷 1-13页

作者： Shayan Bahadori Jonathan mark williams Sarah Collard and Ian Swain Orthopaedic Research Institute Bournemouth UniversityBournemouthDorsetUK Faculty of Health and Social Sciences Bournemouth UniversityBournemouthDorsetUK Faculty of Science and Technology Bournemouth UniversityPooleDorsetUK

Individuals have increasingly high expectations of return to activity following total hip replacement(THR)*** current literature demonstrates marked improvements in pain following ***,there is limited evidence showing objective improvement in daily *** randomized pilot trial aimed to determine the effect of an intervention where outdoor walking distance is used as a goal to increase daily activity of older adults using a commercial activity monitor at 3 to 6 months post *** suggested that the participants in the intervention group had higher activity levels after THR,compared to those in the control *** Cohen’s effect sizes were larger for the changes in the gait,Hip Disability and Osteoarthritis Outcome Score,and Psychosocial Impact of Assistive Devices Scale data in the intervention group in contrast to the control ***,further research with a larger sample size is required to provide tangible evidence on the significance of the effect of the purposeful walk compared to step count.

关键词： return effect sizes

Type 2 autoimmune pancreatitis associated with severe ulcerative colitis: Three case reports

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World Journal of Clinical Cases 2022年第24期10卷 8788-8796页

作者： mark Ghali Karen Bensted David B williams Simon Ghaly Department of Gastroenterology St Vincent's HospitalDarlinghurst 2010NSWAustralia School of Clinical Medicine Faculty of Medicine and HealthThe University of New South WalesSydney 1466NSWAustralia

BACKGROUND Type two autoimmune pancreatitis is a rare and difficult to diagnose,steroid responsive non-IgG4 inflammatory pancreatopathy that can be associated with inflammatory bowel *** SUMMARY This case series describes three cases with varied clinical presentations and representations of autoimmune pancreatitis,and all associated with an aggressive course of ulcerative *** pancreatopathy was independent of bowel disease activity and developed in one case following *** Clinician awareness about this condition is important to allow early diagnosis,treatment and avoid unnecessary pancreatic surgery.

关键词： Autoimmune pancreatitis Inflammatory bowel disease Ulcerative colitis Colectomy Case report

Effect of particle degradation on electrostatic sensor measurements and flow characteristics in dilute pneumatic conveying

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Particuology 2017年第4期15卷 73-79页

作者： Wei Chen Jianyong Zhang Timothy Donohua Kenneth williams Ruixue Cheng mark Jones Bin Zhou Centre for Bulk Solids and Particulate Technologies The University of Newcastle Callaghan 2308 Australia University of Teesside Middlesbrough Cleveland TS1 United Kingdom Southeast University Nanjing 210009 China

Vigorous particle collisions and mechanical processes occurring during high-velocity pneumatic con- veying often lead to particle degradation. The resulting particle size reduction and particle number increase will impact on the flow characteristics, and subsequently affect the electrostatic type of flow measurements. This study investigates this phenomenon using both experimental and numerical meth- ods. Particle degradation was induced experimentally by recursively conveying the fillite material within a pneumatic pipeline. The associated particle size reduction was monitored. Three electrostatic sensors were embedded along the pipeline to monitor the flow. The results indicated a decreasing trend in the electrostatic sensor outputs with decreasing particle size, which suggested the attenuation of the flow velocity fluctuation. This trend was more apparent at higher conveying velocities, which suggested that more severe particle degradation occurred under these conditions. Coupled computational fluid dynamics and discrete element methods （CFD-DEM） analysis was used to qualitatively validate these experimental results. The numerical results suggested that smaller particles exhibited lower flow velocity fluctua- tions, which was consistent with the observed experimental results. These findings provide important information for the accurate aoolication of electrostatic measurement devices in oneumatic conveyors.

关键词： Particle degradation Flow velocity fluctuation Electrostatic sensor CFD-DEM modelling Pneumatic conveying