oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 16 )

2018 ( 181 )

2017 ( 156 )

2016 ( 197 )

Custom range...

Search Results: 1 - 10 of 113404 matches for " W. Van Wijck "
All listed articles are free for downloading (OA Articles)
Page 1 /113404
Display every page Item
SIMPLY OPTIMAL - BEYOND EOQ FOR A POPULAR CLASS OF INVENTORY PROBLEMS
W. Van Wijck
South African Journal of Industrial Engineering , 2012,
Abstract: ENGLISH ABSTRACT: True optimal solution s to real life problems are normally only achievable at the expense of great complexity. Every now and then however, one is almost stunned by the simplicity of a good solution to a practical problem. This paper discusses a relatively simple method for determining the joint optimum order quantity and reorder point for the case where service level is specified as a desired fraction of demand to be satisfied directly from stock. Separate solutions were derived for complete backorders and lost sales, and the method is equally applicable to fixed order quantity and periodic review inventory problems . Demand during the lead time is assumed to be normally distributed . The intent of the paper is to focus on the findings and the application of the method, rather than the mathematical derivation of the formulae itself. AFRIKAANSE OPSOMMING: Ware optimale oplossings vir werklike praktiese probleme is gewoonlik net bereikbaar ten koste van groot kompleksiteit. Elke nou en dan staan 'n mens egter bykans verstom omtrerit die eenvoud van 'n voortreflike oplossing vir 'n bepaalde probleem. Hierdie artikel bespreek 'n relatief eenvoudige metode om die gesamentlike optimale bestel-grootte en veiligheidsvoorraad te bepaal, vir die geval waar dienspeil uitgedruk word as die proporsie van voorraad-items wat op eerste aanvraag direk uit voorraad op hande voorsien word. Aparte oplossings is gevind vir die gevalle van volledige agterstallige bestellings en volledige verlore verkope , en die metode is ewe toepaslik vir vaste bestel-hoeveelheid- en periodieke hersiening-voorraad-stelsels. Die normaal-verdeling is as die statistiese verdeling van aanvraag gedurende die leityd aanvaar, Die artikel fokus op toepassing en bevindings eerder as op die wiskundige afleiding van die formules.
AN EFFECTIVE SCHEDULING SCHEME FOR LIFT CLUBS
W. Van Wijck
South African Journal of Industrial Engineering , 2012,
Abstract: ENGLISH ABSTRACT: This paper describes a formula for scheduling the day-to-day operation of a lift club. The formula is remarkably simple, and can easily be implemented on a spreadsheet. It is also extremely flexible and can cater for almost any peculiarity that may arise. Much like a business, the lift club is viewed as an entity in its own right, rather than as a collection of individuals. The scheme can be used to generate interesting statistics such as percentage utilization of each member, average percentage utilization of all members, effective size of the lift club, etc. In addition, a graph, depicting each member's liability towards the club against time, can be generated. Finally, every member can obtain a record of his/her trip data over any specific period, which may be handy for income tax purposes. AFRIKAANSE OPSOMMING: Hierdie artikel beskryf 'n fonnule vir die dag-tot-dag skedulering van 'n saamryklub. Die fonnule is merkwaardig eenvoudig en kan maklik op 'n sigblad geimplementeer word. Dit is ook besonder buigsaam deurdat dit vir bykans enige gebeurlikheid voorsienning maak. Die voorgestelde skeduleringsmetode beskou die saamryklub as 'n entiteit in eie reg, en skeduleing word vanuit die saamryklub se oogpunt gedoen. Die skema kan gebruik word om interesante statistieke soos byvoorbeeld die persentasie benutting deur enige lid, die gemiddelde persentasie benutting deur aIle lede, die effektiewe grootte van die klub, ens., te genereer. Voorts kan 'n grafiek gegenereer word wat elke lid se aanspreeklikheid teenoor die klub as 'n funksie van tyd grafies vertoon. Laastens kan enige lid op enige stadium 'n rekord trek van die aantal saamrygeleenthede wat hy oor 'n bepaalde periode voorsien en ontvang het. Dit mag handig wees vir belasting doeleindes.
A ZERO SAMPLING PLAN FOR THE MODERATION OF EXAMINATION PAPERS
W. Van Wijck,T. Dirkse van Schalkwyk
South African Journal of Industrial Engineering , 2012,
Abstract: ENGLISH ABSTRACT: Quality assurance within local educational institutions has been under the spotlight in recent years. In particular these institutions are increasingly subjected to minimum standards specified by controlling bodies such as the Higher Education Quality Committee and others. The moderation of examination papers is an important quality assurance activity to ensure that an examination paper’s standard, content, span and marking are fair and reasonable. This paper describes a sampling plan to determine the number of answer books to be checked to confirm that individual marks were awarded correctly. The sampling procedure relates the confidence that marks awarded in a set of examination books meets a specified minimum standard to the number of books moderated. AFRIKAANSE OPSOMMING: Gehalteversekering binne plaaslike opvoedkundige instellings word toenemend onderwerp aan minimum standaarde soos neergelê deur die Kwaliteitskomitee vir Ho r Onderwys en ander. Die moderering van eksamenantwoordstelle is 'n belangrike gehalteversekeringsaktiwiteit wat verseker dat 'n eksamen se standaard, inhoud, bestek en nasien regverdig en redelik is. Die artikel beskryf ‘n steekproefplan vir die proses om individueel toegekende punte vir korrektheid na te gaan. Die voorgestelde prosedure gee die verband tussen die sekerheid dat die punte toegeken deur die eksaminator voldoen aan ‘n gespesifieerde minimum standaard en die aantal boeke wat gemodereer moet word (steekproefgrootte).
CONSTRAINT PROGRAMMING AND UNIVERSITY TIMETABLING
G.W. Groves,W. Van Wijck
South African Journal of Industrial Engineering , 2012,
Abstract: ENGLISH ABSTRACT: The technology of Constraint Programming is rapidly becoming a popular alternative for solving large-scale industry problems. This paper provides an introduction to Constraint Programming and to Constraint Logic Programming (CLP), an enabler of constraint programming. The use of Constraint Logic Programming is demonstrated by describing a system developed for scheduling university timetables. Timetabling problems have a high degree of algorithmic complexity (they are usually NP-Complete), and share features with scheduling problems encountered in industry. The system allows the declaration of both hard requirements, which must always be satisfied, and soft constraints which need not be satisfied, though this would be an advantage. AFRIKAANSE OPSOMMING: Hierdie artikel beskryf ’n familie van probleem-oplossingstegnieke bekend as “Constraint Programming”, wat al hoe meer gebruik word om groot-skaalse industri le probleme op te los. Die nut van hierdie tegnieke word gedemonstreer deur die beskrywing van ’n skeduleringsisteem om die roosters vir ’n universiteit te genereer. Roosterskeduleringsprobleme is in praktiese gevalle NP-volledig en deel baie eienskappe met industri le skeduleringsprobleme. Die sisteem wat hier beskryf word maak gebruik van beide harde beperkings (wat altyd bevredig moet word) en sagte beperkings (bevrediging hiervan is wel voordelig maar dit is opsioneel.)
A COST OPTIMISED PROCESS MEAN SET POINT FOR TWO SIDED SPECIFICATIONS
W. Van Wijck,M. Von Benecke
South African Journal of Industrial Engineering , 2012,
Abstract: ENGLISH ABSTRACT: This paper describesthe derivationof cost minimisingexpressions to optimallyset the processmeanof a manufacturing processrestrictedby a double-sidedspecification. Two scenariosare considered. For the first scenario,multiplereworkingiterationsare possible,while in the second,only one rework opportunityis allowed. A numericalexampleis also presented. Resultswere obtainedby numerical solutionand are presentedin graphicalformat. AFRIKAANSE OPSOMMING: Hierdieartikelbeskryfdie afleidingvan koste-minimerende uitdrukkings wat die proses-gemiddelde van 'n vervaardigingsproses wat deur 'n twee-kantige spesifikasie beperk word,optimaaldaar stel. Twee gevalleword oorweeg. In die eerstegeval is verskeieherwerk-iterasies moontlik,terwyl die tweede gevalslegs een herwerk-geleentheid aanvaar. 'n Numeriesevoorbeeldwordook bespreek. Resultate is deur numerieseanaliseverkry en word grafiesvoorgestel.
3D-FEATURE RECOGNITION FROM MEASURED DATA
M. Janssens,W. Van Wijck,N.D. Du Preez
South African Journal of Industrial Engineering , 2012,
Abstract: ENGLISH ABSTRACT: This paper presents a method to automatically extract analytical entities like planes, spheres and cylinders from a file containing a cloud of points. The method facilitates the manipulation and reduction of large data sets and the evaluation of it. It can be used as a design tool, a quality control tool, data-processing tool or a data reduction tool. From a database of points, the user can automatically extract a subset of points belonging to an analytical entity of interest, within a predefined but adjustable level of confidence. If necessary, the dimensional parameters of the entity can also be calculated. The method is based on the subtle statistical properties of the least-squares technique that makes it compliant with the strict regulations in the co-ordinate measuring arena. Its robustness guarantees . the applicability to less accurate environments than precision engineering. AFRIKAANSE OPSOMMING: Hierdie artikel bespreek 'n metode met behulp waarvan analitiese voorwerpe soos vlakke, sfere en silinders outomaties vanuit 'n wolk van datapunte, onttrek kan word. Die metode is geskik vir die hantering, manipulasie, reduksie en evaluasie van groot data-stelle. Dit kan gebruik word as 'n gereedskapstuk vir ontwerp, gehaltebeheer, dataverwerking en data-reduksie. Gegewe 'n databasis van punte, kan die gebruiker die subset van punte wat tot enige analitiese voorwerp van belang behoort, outomaties binne 'n voorafgespesifiseerde, maar verstelbare, vlak van vertroue onttrek. Hierbenewens en indien nodig, kan die dimensionele parameters en afmetings van die betrokke entiteit ook bereken word. Die algoritme maak van die kleinste-kwadrate metode gebruik, sodat elke passings-parameter statisties kwantifiseerbaar en verantwoordbaar is. In hierdie opsig voldoen dit aan die streng regulasies wat die koordinaat-meet arena kenmerk. Die robuustheid van die metode, maak dit ook geskik vir toepassing in minder akkurate omgewings as presisie-ingenieurswese,
The PINE study: rationale and design of a randomised comparison of epidural injection of local anaesthetics and steroids versus care-as-usual to prevent postherpetic neuralgia in the elderly [ISRCTN32866390]
Opstelten Wim,van Wijck Albert,van Essen Gerrit,Buskens Erik
BMC Anesthesiology , 2004,
Abstract: Background Postherpetic neuralgia (PHN) is by far the most common complication of herpes zoster (HZ) and one of the most intractable pain disorders. Since PHN is seen most often in the elderly, the number of patients with this disorder is expected to increase in our ageing society. PHN may last for months to years and has a high impact on the quality of life. The results of PHN treatment are rather disappointing. Epidural injection of local anaesthetics and steroids in the acute phase of HZ is a promising therapy for the prevention of PHN. Since randomised trials on the effectiveness of this intervention are lacking, the PINE (Prevention by epidural Injection of postherpetic Neuralgia in the Elderly) study was set up. The PINE study compares the effectiveness and cost-effectiveness of a single epidural injection of local anaesthetics and steroids during the acute phase of HZ with that of care-as-usual (i.e. antivirals and analgesics) in preventing PHN in elderly patients. Methods / design The PINE study is an open, multicenter clinical trial in which 550 elderly (age ≥ 50 yr.) patients who consult their general practitioner in the acute phase of HZ (rash < 7 days) are randomised to one of the treatment groups. The primary clinical endpoint is the presence of HZ-related pain one month after the onset of the rash. Secondary endpoints include duration and severity of pain, re-interventions aiming to treat the existing pain, side effects, quality of life, and cost-effectiveness. Conclusion The PINE study is aimed to quantify the (cost-) effectiveness of a single epidural injection during the acute phase of HZ on the prevention of PHN.
Polyethylene glycol versus dual sugar assay for gastrointestinal permeability analysis: is it time to choose?
van Wijck K,Bessems BAFM,van Eijk HM,Buurman WA
Clinical and Experimental Gastroenterology , 2012,
Abstract: Kim van Wijck,1,2 Babs AFM Bessems,2 Hans MH van Eijk,2 Wim A Buurman,2 Cornelis HC Dejong,1,2 Kaatje Lenaerts1,21Top Institute Food and Nutrition, Wageningen, The Netherlands; 2Department of Surgery, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center, Maastricht, NetherlandsBackground: Increased intestinal permeability is an important measure of disease activity and prognosis. Currently, many permeability tests are available and no consensus has been reached as to which test is most suitable. The aim of this study was to compare urinary probe excretion and accuracy of a polyethylene glycol (PEG) assay and dual sugar assay in a double-blinded crossover study to evaluate probe excretion and the accuracy of both tests.Methods: Gastrointestinal permeability was measured in nine volunteers using PEG 400, PEG 1500, and PEG 3350 or lactulose-rhamnose. On 4 separate days, permeability was analyzed after oral intake of placebo or indomethacin, a drug known to increase intestinal permeability. Plasma intestinal fatty acid binding protein and calprotectin levels were determined to verify compromised intestinal integrity after indomethacin consumption. Urinary samples were collected at baseline, hourly up to 5 hours after probe intake, and between 5 and 24 hours. Urinary excretion of PEG and sugars was determined using high-pressure liquid chromatography-evaporative light scattering detection and liquid chromatography-mass spectrometry, respectively.Results: Intake of indomethacin increased plasma intestinal fatty acid-binding protein and calprotectin levels, reflecting loss of intestinal integrity and inflammation. In this state of indomethacin-induced gastrointestinal compromise, urinary excretion of the three PEG probes and lactulose increased compared with placebo. Urinary PEG 400 excretion, the PEG 3350/PEG 400 ratio, and the lactulose/rhamnose ratio could accurately detect indomethacin-induced increases in gastrointestinal permeability, especially within 2 hours of probe intake.Conclusion: Hourly urinary excretion and diagnostic accuracy of PEG and sugar probes show high concordance for detection of indomethacin-induced increases in gastrointestinal permeability. This comparative study improves our knowledge of permeability analysis in man by providing a clear overview of both tests and demonstrates equivalent performance in the current setting.Keywords: gastrointestinal permeability, polyethylene glycol, dual sugar
Augmented visual feedback of movement performance to enhance walking recovery after stroke: study protocol for a pilot randomised controlled trial
Thikey Heather,Grealy Madeleine,van Wijck Frederike,Barber Mark
Trials , 2012, DOI: 10.1186/1745-6215-13-163
Abstract: Background Increasing evidence suggests that use of augmented visual feedback could be a useful approach to stroke rehabilitation. In current clinical practice, visual feedback of movement performance is often limited to the use of mirrors or video. However, neither approach is optimal since cognitive and self-image issues can distract or distress patients and their movement can be obscured by clothing or limited viewpoints. Three-dimensional motion capture has the potential to provide accurate kinematic data required for objective assessment and feedback in the clinical environment. However, such data are currently presented in numerical or graphical format, which is often impractical in a clinical setting. Our hypothesis is that presenting this kinematic data using bespoke visualisation software, which is tailored for gait rehabilitation after stroke, will provide a means whereby feedback of movement performance can be communicated in a more meaningful way to patients. This will result in increased patient understanding of their rehabilitation and will enable progress to be tracked in a more accessible way. Methods The hypothesis will be assessed using an exploratory (phase II) randomised controlled trial. Stroke survivors eligible for this trial will be in the subacute stage of stroke and have impaired walking ability (Functional Ambulation Classification of 1 or more). Participants (n = 45) will be randomised into three groups to compare the use of the visualisation software during overground physical therapy gait training against an intensity-matched and attention-matched placebo group and a usual care control group. The primary outcome measure will be walking speed. Secondary measures will be Functional Ambulation Category, Timed Up and Go, Rivermead Visual Gait Assessment, Stroke Impact Scale-16 and spatiotemporal parameters associated with walking. Additional qualitative measures will be used to assess the participant’s experience of the visual feedback provided in the study. Discussion Results from the trial will explore whether the early provision of visual feedback of biomechanical movement performance during gait rehabilitation demonstrates improved mobility outcomes after stroke and increased patient understanding of their rehabilitation. Trial registration Current Controlled Trials ISRCTN79005974
Polyethylene glycol versus dual sugar assay for gastrointestinal permeability analysis: is it time to choose?
van Wijck K, Bessems BAFM, van Eijk HM, Buurman WA, Dejong CH, Lenaerts K
Clinical and Experimental Gastroenterology , 2012, DOI: http://dx.doi.org/10.2147/CEG.S31799
Abstract: lyethylene glycol versus dual sugar assay for gastrointestinal permeability analysis: is it time to choose? Original Research (1328) Total Article Views Authors: van Wijck K, Bessems BAFM, van Eijk HM, Buurman WA, Dejong CH, Lenaerts K Published Date July 2012 Volume 2012:5 Pages 139 - 150 DOI: http://dx.doi.org/10.2147/CEG.S31799 Received: 15 March 2012 Accepted: 30 April 2012 Published: 19 July 2012 Kim van Wijck,1,2 Babs AFM Bessems,2 Hans MH van Eijk,2 Wim A Buurman,2 Cornelis HC Dejong,1,2 Kaatje Lenaerts1,2 1Top Institute Food and Nutrition, Wageningen, The Netherlands; 2Department of Surgery, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center, Maastricht, Netherlands Background: Increased intestinal permeability is an important measure of disease activity and prognosis. Currently, many permeability tests are available and no consensus has been reached as to which test is most suitable. The aim of this study was to compare urinary probe excretion and accuracy of a polyethylene glycol (PEG) assay and dual sugar assay in a double-blinded crossover study to evaluate probe excretion and the accuracy of both tests. Methods: Gastrointestinal permeability was measured in nine volunteers using PEG 400, PEG 1500, and PEG 3350 or lactulose-rhamnose. On 4 separate days, permeability was analyzed after oral intake of placebo or indomethacin, a drug known to increase intestinal permeability. Plasma intestinal fatty acid binding protein and calprotectin levels were determined to verify compromised intestinal integrity after indomethacin consumption. Urinary samples were collected at baseline, hourly up to 5 hours after probe intake, and between 5 and 24 hours. Urinary excretion of PEG and sugars was determined using high-pressure liquid chromatography-evaporative light scattering detection and liquid chromatography-mass spectrometry, respectively. Results: Intake of indomethacin increased plasma intestinal fatty acid-binding protein and calprotectin levels, reflecting loss of intestinal integrity and inflammation. In this state of indomethacin-induced gastrointestinal compromise, urinary excretion of the three PEG probes and lactulose increased compared with placebo. Urinary PEG 400 excretion, the PEG 3350/PEG 400 ratio, and the lactulose/rhamnose ratio could accurately detect indomethacin-induced increases in gastrointestinal permeability, especially within 2 hours of probe intake. Conclusion: Hourly urinary excretion and diagnostic accuracy of PEG and sugar probes show high concordance for detection of indomethacin-induced increases in gastrointestinal permeability. This comparative study improves our knowledge of permeability analysis in man by providing a clear overview of both tests and demonstrates equivalent performance in the current setting.
Page 1 /113404
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.