Lapping Movement Research Articles

Modeling of double-layer jacquard fabrics for pattern simulation

PurposeDouble-jacquard technique is referred as the most advanced technology for forming patterns on both layers of a 3D fabric knitted on a double-needle bar warp-knitting machine. In order to realize the computer-aided design and simulation of jacquard patterns, the purpose of this paper is to propose a mathematic model for representation of jacquard structures and an improved mass-spring model to improve the simulation of structural deformation behavior.Design/methodology/approachPrimarily, it analyzes the jacquard patterning method and displacing principle to design jacquard structures on each layer and linking structures of two layers. Based on that, a loop geometry defined by six key points and segmental lines is built to transfer the jacquard bitmap and lapping movements into a fabric of loops and therefore realizing patterns visualization. Afterwards, an improved mass-spring model is built to simulate structural deformation, in which the fabric is simplified as a mesh of uniformly distributed mass particles. Each loop is treated as a massless particle while underlaps are referred as structural springs connecting loops particles. Elastic forces of these springs on each loop particle is calculated according to the Hook’s law and Newton’s second law, and then based on the explicit Euler’s equations, motion state of each particle is solved including the velocity and the shift.FindingsBased on the above method, a simulator for double-layer jacquard fabrics is developed via Visual C++ language to visualize the patterned fabrics with pitting effects. With a jacquard shoe fabric as an example, this simulation model is proved to be practical and efficient by comparing the simulation result and real fabric.Research limitations/implicationsBecause of limited researches, 3D simulation modeling of this double-layer jacquard fabric will be studied in the further research.Practical implicationsThe implement of this simulation method will offer the industries a time-saving and cost-saving approach for new fabrics development.Originality/valueThis approach can be used as a reference for simulating other knitted fabrics with jacquard patterns, such as jacquard garment fabrics and home textile fabrics.

Models for basic warp knitted fabrics Part II: single guide bar fabrics (closed-lap and open-lap)

Warp knitted fabrics are mainly used as household goods, technical textiles, medical textiles, etc. Modeling of these fabrics is necessary for predicting the desired technical or medical functions beforehand. In this context, the present series of papers is devoted to the modeling of basic warp knitted fabrics. In this, Part II of this series, models for single guide bar fabrics are created. There are mainly two types of single bar fabrics, namely closed-lap and open-lap single bar fabrics. Structures are also changed by having different lapping movements up to the five needle spaces. In this work, 1 and 1, 2 and 1, 3 and 1, 4 and 1 closed-lap and 1 and 1, 2 and 1, 3 and 1 open-lap single bar warp knitted fabrics are considered. During modeling, the loop leanings in the course-wise direction are considered, curvature equalities at the loop parts are attained as much as possible, two connected parabolas are taken as the fabric plane model of the loop connection part, loop heads are taken as parametric ellipses in two dimensions and the remaining loop parts are modeled by wrapping parabolic or cubic curves on imaginary cylindrical or conical objects. The models created are versatile and they can be changed and used for special cases. The models created are drawn to scale by using the 3DS-MAX computer graphical program. At first glance, it is seen that the shapes obtained by the models are similar to the ones that can be observed in real samples.

Research on Ultrasonic-Assisted Fixed-Abrasive Lapping Technology for Engineering Ceramics Cylindrical Part

Lapping is a key processing step for precision parts, which directly affects machining quality, precision, and efficiency. Due to some drawbacks of free-abrasive lapping such as deep scratches on the lapped surface, lower lapping efficiency for lower lapping speed, severe waste of abrasive, high-processing cost, and so on, conventional fixed-abrasive lapping (CFL) technology was proposed and developed recently. Meanwhile, considering the unique advantages of the ultrasonic-assisted machining during the processing of those hard and brittle materials and the effect of ultrasonic vibration on the self-sharpening characteristic of abrasive pellet, a novel ultrasonic-assisted fixed-abrasive lapping (UAFL) technology is put forward and corresponding lapping device for engineering ceramics cylindrical part is developed in this paper. Meanwhile, UAFL mechanism and characteristics were studied theoretically and experimentally. Research results show that superimposed ultrasonic vibration changes the lapping movement characteristics and material removal mechanism to a certain extent, helping to heighten material removal rate, smoothen the waveform of tangential force, reduce the average tangential force, and improve surface machining quality. UAFL can be regarded as a high efficiency and precision processing technology for engineering ceramics cylindrical part.

Theoretical modeling of spacer-yarn arrangement for warp-knitted spacer fabrics and experimental verification

Different surface structure of spacer fabric implies different spacer yarn arrangement and therefore the compression resistance of fabric. The spacer yarns' arrangement modeling of warp knitted spacer fabrics having identical parameters (thickness, density, material etc.) but different surface structures on double-needle-bar Raschel knitting machine is presented in the study. In a sample, there are several spacer yarns' inclination directions, which differ according to surface structures despite the same lapping movement of spacer guide bars. To simplify the arrangement modeling, it was considered that there was only one inclination angle in a sample, and that was weighted average angle η. The theoretical compression curves were obtained by substituting η into derived equation then simulating by Matlab. To verify proposed arrangement modeling, the compression experiment was done to gain experimental compression curves. The curves of theoretical simulation and experiment of each sample were compared in a figure and the curves exhibited agreement with each other while there were still some deviations derived from the partial approximate substitutions of equations and arrangement angles, as well as the differences between theoretical and actual fabric parameters after removing from knitting machine such as thickness, density, and so on.

Pacing and lapping movements among institutionalized patients with dementia.

Wandering is a complex behavior, and defining wandering has been challenging. The current study used the integrated circuit (IC) tag monitoring system to describe the distance moved per day and the spatial movements of patients with dementia. The study was conducted in a 60-bed semiacute dementia care unit in a general hospital in Japan over a 3-month period in 2006. The distance moved per day, the numbers of pacing and lapping movements, and the proportions of the distance moved that was paced or lapped were tabulated in 23 patients diagnosed with dementia. The distance moved per day and the numbers of pacing and lapping movements varied greatly within and among study participants. The median distance moved per day was inversely correlated with participants' age and Mini-Mental State Examination (MMSE) scores (adjusted r(2) = .34, P = .01). Consecutive lapping and pacing movements were rare patients with in Alzheimer's disease (AD), while 2 patients with frontotemporal dementia paced or lapped repeatedly.

Effect of Manufacturing Parameters on the Tensile Properties and Yarn Damage of Glass Fiber Warp-knitted Net Preforms

Knitted fabric reinforcements gain interest in the composite industry for their excellent drapability, impact resistance, and net-shape manufacturability. Much research on the mechanical properties of knitted fabric reinforced thermoset and thermoplastic composites are available in the literature. However, to reduce the complexity in analysis and calculation, the loop architectures studied in these researches, either weft-knit or warp-knit, were very simple and lack of diversity. Additionally, limited attention has been given to the glass yarn damage during knitting, which have been proved to have a significant effect on the performance of the final composites. In this article, six-bar warp-knitted net preforms fabricated of glass plied yarns were studied. Eleven kinds of net preforms with different lapping movements, different take-up values, and different run-in ratios were fabricated and their mechanical performances as well as yarn damage during knitting were evaluated. The results showed that yarn damage and preform performance are highly related with the manufacture parameters from which optimum machine settings for each kind of preform could be delivered.

Cortically induced postsynaptic potentials in hypoglossal motoneurons after axotomy

Cortically induced postsynaptic potentials were studied in normal and axotomized cat hypoglossal motoneurons. In normal protruder motoneurons innervating tongue protruder muscles, we have demonstrated that stimulation of the orbital gyrus, at the point optimum for inducing lapping movements of the tongue by repetitive stimuli, produced inhibitory postsynaptic potentials or excitatory postsynaptic potentials followed by predominant inhibitory postsynaptic potentials. The cortically induced excitatory postsynaptic potential in normal protruder motoneurons was composed of only the short-latency component. In protruder motoneurons 30, 40, 60 and 80 days after axotomy, we have demonstrated that the number of protruder motoneurons responding with two components of excitatory postsynaptic potentials (the short- and the long-latency component) to cortical stimulation increased in correspondence with the lapse of days after axotomy and that the amplitude of cortically induced inhibitory postsynaptic potentials in axotomized protruder motoneurons was reduced in size as compared with normal protruder motoneurons.

The Ingestion of Dry Sugars by Adult Entomophagous Insects and the Use of This Feeding Habit for Measuring the Moisture Needs of Parasites1

The belief that adult insect parasites must acquire their foods from liquid or semifluid sources has made it difficult to assess accurately the moisture needs of different entomophagous species. It was found that many adult entomophagous insects can feed upon completely dry sugar. Parasitic Hymenoptera dissolve the dry sugar with a lapping movement of the glossa moistened with salivary fluids. Some adult predators use regurgitated fluids for dissolving the sugar before its ingestion. By comparing the survival of adult parasites supported on dry sugar at 0% relative humidity with that of adults given moist sugar at optimum moisture conditions, the aridity tolerance of a species may be assessed without interference by starvation or by liquid food intake. Examples of the use of this simple method for assessing the moisture needs of four species of parasites are presented.