Modelling the pattern creation process for the optimum design of a circular warp-knitting machine using a conical needle-bed

A circular warp-knitting machine was designed using a novel approach that uses a conical needle-bed. This machine was built and successfully tested. The interaction between the patterning and knitting mechanisms of a warp-knitting machine is critical for the performance of the machine. In a circular warp-knitting machine, geometric parameters such as the diameter of the patterning rings and the distance between the patterning rings and the needles can significantly affect the patterning capability of the machine. This paper describes an approach to modelling the yarn and needle paths in a novel circular warp knitting machine with a conical needle-bed and patterning rings, using equations that govern the relationship between the different geometric parameters in order to calculate the amplitude of the shogging movements and optimise machine performance. A set of mathematical equations governing the geometric relationship that determines the limits of the motion of the patterning rings is presented. The algorithms have been created and successfully tested using a case study. A mathematical model and appropriate algorithms are developed that prove useful design tools for the designer of the circular warp knitting machines using conical needle-bed

Optimising cam motion using piecewise polynomials

The paper presents a method of synthesising cam profiles based on the use of piecewise polynomials together with an optimisation technique. Special cases and limitations are discussed and illustrated, making the procedure complete and systematic for any design requirements. Using piecewise polynomials, the complete cam profile can be designed as a combined linear system. The optimisation technique described goes even further, manipulating the variables in the linear system to select the ideal combination. In addition, a means to prove the validity of the results is explained

Imagerie dans le cathétérisme des cardiopathies congénitales : place de l’échocardiographie 3D transthoracique

RésuméL’échocardiographie 3D transthoracique a longtemps été freinée dans son développement en raison de conditions techniques d’acquisition compliquées et de qualité d’images médiocres. L’avènement des sondes matricielles permet au 3D en devenant temps réel d’entrer dans la pratique clinique courante. Si la voie œsophagienne a permis au 3D de trouver ses lettres de noblesses par ses descriptions anatomiques uniques des valves et des septa, l’échocardiographie transthoracique peut désormais se décliner en modes 2D, Doppler et 3D. Ses applications dans la cardiologie congénitale et pédiatrique sont multiples : description anatomique précise des défauts septaux auriculaires et ventriculaires, classification des bicuspidies aortiques et analyse du mécanisme de sténose. Ainsi, l’échocardiographie 3D permet-elle de sélectionner de façon non invasive les patients, de guider et de juger du résultat d’un cathétérisme interventionnel. L’imagerie 3D est un excellent moyen de communication entre l’imageur et le cardiologue interventionnel mais aussi de délivrer des informations claires au patient et à la famille avant et après un cathétérisme.SummaryThree-dimensional echocardiography has improved dramatically due to technical advances in probe design and computer processing. The introduction of real time 3D echocardiography has led to its use in everyday clinical practice. Congenital heart disease demands a detailed understanding of the spatial relationships of cardiac structures to plan treatment. The introduction of new transthoracic 3D probes has extended the applications to real-time guidance of catheter procedures. Prominent among the cardiac lesions which have been studied are: atrial septal defects, ventricular septal defects and stenotic bicuspid aortic valves. Its values should be decisive in many congenital cardiac lesions requiring interventional catheterisation. 3D echocardiography is an easy way to communicate to the patient and its family about the pathology

Design and development of a novel circular warp knitting machine

This paper reports the design, manufacture and test of an innovative method of producing warp knitting fabrics, using a circular disposition of the needles rather than linear needle bars. By using the novel truncated-cone needle-bed concept instead of a cylindrical one, the needles slide simultaneously in radial and vertical directions to combine the reciprocating and swinging motions into one. Initially a mechanical prototype machine was designed, built and successfully tested to prove the knitting mechanism and its interaction with the patterning rings. The second prototype has a mechatronic patterning mechanism, hence increasing the patterning capabilities significantly, and enabling changing fabric pattern change during knitting without requiring long machine stoppages and cam changes

Numerical study of strength mismatch in cross-weld tensile testing

The strength mismatch effect on the deformation behaviour of defect-free cross-weld tensile specimens, where there is a variation in strength along the length of the specimen, was investigated through 2D finite element analysis. A simple bi-material model, which is generally used in current engineering assessments (e.g. R6 “Assessment of the integrity of structures containing defects”) to examine the strength mismatch effect on the deformation and fracture behaviour of a weld which actually includes a heat-affected-zone, could lead to non- conservative or overly conservative predictions. In fusion welded components, one would generally observe that there is a heat-affected zone where the material properties are different from the weld and base material, and there is a continuous gradient of properties between the two. The material properties in HAZ are generally assigned discretely; however, in our multi-material model these properties are successfully assigned continuously by embedding subroutines into finite element model. This multi-material approach was used to examine the effect of strength mismatch on the local and global deformation behavior of fusion welds. It has been found that the bi-material modeling, by ignoring the HAZ, and multi-material discrete HAZ modeling of the cross-weld specimens leads to unrealistically biaxial stresses at the interfaces where there is an abrupt variation of the material properties. However, multi- material continuous HAZ modeling eliminates unrealistic stress biaxiality and enables to examine the local deformation more accurately. It was also found that the global stress-strain behaviour obtained using the bi- material and multi-material modeling is different

Detecting anomalous energy consumption in android applications

The use of powerful mobile devices, like smartphones, tablets and laptops, are changing the way programmers develop software. While in the past the primary goal to optimize software was the run time optimization, nowadays there is a growing awareness of the need to reduce energy consumption. This paper presents a technique and a tool to detect anomalous energy consumption in Android applications, and to relate it directly with the source code of the application. We propose a dynamically calibrated model for energy consumption for the Android ecosystem, and that supports different devices. The model is then used as an API to monitor the application execution: first, we instrument the application source code so that we can relate energy consumption to the application source code; second, we use a statistical approach, based on fault-localization techniques, to localize abnormal energy consumption in the source code

ACT variation after a weight-based heparin bolus before CPB is not predictable in infant

BackgroundIn pediatric cardiac surgery, anticoagulation protocols are derived from adult protocols. Age, Antithrombin III level, and capacity to generate thrombin are factors that affect unfractionated heparin (UFH) action in children. A starting UFH dose of 400 UI/kg is recommended to get an Activated Clotting Time (ACT) target over 400seconds. In our daily practice, we noticed a wide range of ACT increase (ΔACT) after this standardized weight based bolus of UFH.ObjectiveTo define factors affecting UFH effectiveness based on ΔACT before CPB initialization in pediatric cardiac surgery.MethodsA retrospective chart review of patient undergoing cardiac surgery requiring CPB in a single university hospital was performed. Patients receiving preoperative anticoagulation therapy or platelet aggregation inhibitors were excluded. We searched predictive factors for ΔACT. We defined 2 groups: hyperrespondents (HR; ΔACT>500) and normorespondents (NR; ΔACT<500).ResultsSeventy-nine charts were reviewed. Median [25–75] age and weight were respectively 13.8 [5–72] months and 8.7 kg [5.5–18.8]. UFH pre CPB bolus was 384 [358–410] to increase pre operative ACT from 124 [115–137] to 536 s[463–582]. HR are younger (4.9 [3.7–13] vs 24.6 [5.7–76] months, P<0.05) and have smaller weight (6,1 [4.6–7.8] vs 10 kg[5,8–19.5], P<0,05) than NR. ΔACT is correlated to UFH dose for patients>5 months (r=0.59 P=0.00001) and>5kg (r=0.54 P=0.00001) for with a predictive ΔACT of 386 s [325–443]. There is no correlation between ΔACT and UFH dose for patients<5 months and<5kg.ConclusionA dose UFH of 400 UI/kg before starting CPB in pediatrics is overestimated, especially for children<5 months and<5kg. Accurate dose for ACT target>400 s in this specific population should be calculated using other method that still needs to be developed to avoid complications associated to excessive dose of UFH