Thread Length Research Articles

Experimental and Modeling Study of Breakup Behavior in Silicone Jet Dispensing for Light-Emitting Diode Packaging

Silicone jet dispensing has grown increasingly common in light-emitting diode (LED) packaging owing to its high speed and low cost. However, differences in breakup behavior result in different silicone jetting volumes that create challenges in maintaining dispensing volume consistency during silicone jet dispensing process; this severely affects the performance of LED packaging. To reveal the breakup behavior during the jet dispensing process, the experimental and modeling studies were conducted. First, the ultrafast breakup process was experimentally observed using a high-speed camera, which shows that this process only requires approximately 50 ms. Then, an analytical model was developed and verified through an experiment. Using this analytical model, the effects of initial disturbance amplitude, initial disturbance wavelength, and thread length on the thread breakup were studied. The simulation demonstrated that it is necessary to control the disturbance amplitude under 0.005 for volume consistency in jet dispensing; thus, a moving work piece rather than a moving nozzle is recommended in jet dispensing. A disturbance wavelength between 0.3 and 0.6 mm is beneficial for both thread breakup and high-volume consistency. Thread length has little effect on the breakup position but significant effects on the volume consistency and breakup time. A low substrate increases the volume and the consistency of thread breakup. This paper will provide a useful guide for dispenser designs of modern LED packages.

An experimental study of dynamics of towed flexible cylinders

In this paper, some experiments are described which were designed to illustrate the dynamical behaviour of towed flexible cylinders and to test the theory. A silicone rubber cylinder was manufactured such that it was almost neutrally buoyant when immersed in water. The cylinder was terminated by plexiglas end-pieces and was held in horizontal water flow by a length of nylon thread (towrope). Video capturing along with image processing techniques were used to measure the transverse displacement of the cylinder in the horizontal plane. For the cylinder with relatively streamlined nose and tail end-pieces, non-flexural (rigid-body), as well as flexural instabilities developed as the flow velocity was increased; shortening the towrope was not very effective for stabilizing the system, but a sufficiently blunt tail end-piece had a very significant stabilizing effect. The experimental observations are generally in qualitative agreement with the available nonlinear theory. Quantitative comparison of various quantities, e.g. the instability thresholds, between experiment and theory, based on the estimated values of some of the theoretical nondimensional parameters, is also fairly good.

Uncovering changes in spider orb-web topology owing to aerodynamic effects.

An orb-weaving spider's likelihood of survival is influenced by its ability to retain prey with minimum damage to its web and at the lowest manufacturing cost. This set of requirements has forced the spider silk to evolve towards extreme strength and ductility to a degree that is rare among materials. Previous studies reveal that the performance of the web upon impact may not be based on the mechanical properties of silk alone, aerodynamic drag could play a role in the dissipation of the prey's energy. Here, we present a thorough analysis of the effect of the aerodynamic drag on wind load and prey impact. The hypothesis considered by previous authors for the evaluation of the drag force per unit length of thread has been revisited according to well-established principles of fluid mechanics, highlighting the functional dependence on thread diameter that was formerly ignored. Theoretical analysis and finite-element simulations permitted us to identify air drag as a relevant factor in reducing deterioration of the orb web, and to reveal how the spider can take greater-and not negligible-advantage of drag dissipation. The study shows the beneficial air drag effects of building smaller and less dense webs under wind load, and larger and denser webs under prey impact loads. In essence, it points out why the aerodynamics need to be considered as an additional driving force in the evolution of silk threads and orb webs.

P29.09: The incidence and etiology of an embedded Intrauterine device (IUD) with a 3D ultrasound study

The classical recommended follow up of an IUD is to perform ultrasound if suspicion of perforation during insertion or anomalies in the thread length. Recent studies show that IUD embedded is a possible cause of pain or bleeding Benaceraf et al. The aim of our study is to evaluate the incidence of symptomatic and asymptomatic IUD embedded using 3D ultrasound. Seventy four consecutive women with a T shaped IUD coming for routine annual follow up have a clinical history of pain and abnormal bleeding, and a thread length and 3D ultrasound to check IUD malposition. A 3D reconstructed coronal view was performed and the IUD was considered embedded when any part extended past the cavity into the myometrium or the cervix. The width measurement was taken on the coronal view. Among the 74 consecutive women with IUD evaluated by 3D reconstructed coronal view, 14 (18.9%) had IUD located within the myometrium. 11 (14.8%) had asymptomatic IUD embedded and 3 (4%) had symptomatic (2 with pain or 1 with abnormal bleeding) IUD embedded. 3 embedded symptomatic IUD out of 14 embedded IUD (21%) have their symptoms improved when IUD was removed or replaced. The mean width of the fundal endometrial cavity with a normal placed IUD is 30.4 ± 4.5 mm compared to a embedded IUD is 25.1 ± 6.8 mm (p = 0.001). Only 25 out of 74 (34%) have their fundal endometrial cavity more than 32 mm witch is the width of the T shaped IUD placed in our series. All thread where normally located. An embedded IUD is present in one out of five women with a T shaped IUD and a possible cause of pelvic pain and bleeding. To avoid this complication we should measure the width of the fundal endometrial cavity and choose an adapted size IUD.

Microcrystalline Cellulose from Plant Wastes through Sodium Hydroxide-Anthraquinone-Ethanol Pulping

Microcrystalline cellulose was prepared from wastes of Tithonia diversifolia, inflorescence stems of Musa sapientum, and Musa paradisiaca by soda-anthraquinone–ethanol pulping method. They were bleached by sodium chlorite and then alpha-cellulose was isolated, followed by preparation of microcrystalline cellulose. The study revealed the effect of various processing stages on the properties of the cellulose obtained. Yields of more than 80% of microcrystalline cellulose were obtained. Fourier transform infrared (FTIR) and solid state 13C Nuclear magnetic resonance (13C NMR) confirmed the presence of the major expected peaks in microcrystalline cellulose. Scanning electron microscopy (SEM) revealed that Musa species had short fiber length and mixtures of non-aggregated spherical, rod-shaped and thread like microcrystalline cellulose, but Tithonia diversifolia had aggregate crystal packed formation. The results compared well with those of other authors and were able to meet most of the requirements specified in British Pharmacopoeia. The study revealed that a drug excipient like microcrystalline cellulose that could protect thermo-labile active ingredients could be successfully obtained from abundant non-woody agricultural wastes.

Study on dynamic needle thread tensions in a single needle lock stitch (SNLS) sewing machine. I. Effect of stitch length, check spring tension, fabric feed timing and needle thread in-take length

This paper, the first of a two-part series, aims to find the effect of stitch length, check spring tension, fabric feed timing and needle thread in-take length on tension peaks occurring on a spun polyester needle thread during a sewing cycle of a SNLS sewing machine. The pre-tensions on the bobbin and needle threads and sewing speed were kept constant. A PC interfaced measuring instrument was fabricated to measure dynamic sewing tension on needle thread above the needle bar. Four prominent tension peaks were detected. Longer stitch length causes higher tension peaks; and shorter length stitch requires higher pre-tension to obtain a balanced stitch. The check spring tension has no effect on tightening tension. Incorrect timing of feed dog can cause very high tightening tension. The change in the position of thread length guide alters the friction of needle thread at critical guides which determines the length of thread to be released through tensioner; release of longer length of thread results in lower tension peaks (1, 2 and 4) and vice versa.

Dependence of the length of solar filament threads on the magnetic configuration

High-resolution Hα observations indicate that filaments consist of an assembly of thin threads. In quiescent filaments, the threads are generally short, whereas in active region filaments, the threads are generally long. In order to explain these observational features, we performed one-dimensional radiative hydrodynamic simulations of filament formation along a dipped magnetic flux tube in the framework of the chromospheric evaporation-coronal condensation model. The geometry of a dipped magnetic flux tube is characterized by three parameters, i.e., the depth (D), the half-width (w) and the altitude (h) of the magnetic dip. A survey of the parameters in numerical simulations shows that when allowing the filament thread to grow in 5 days, the maximum length (Lth) of the filament thread increases linearly with w, and decreases linearly with D and h. The dependence is fitted into a linear function Lth = 0.84w − 0.88D − 2.78h+17.31(Mm). Such a relation can qualitatively explain why quiescent filaments have shorter threads and active region filaments have longer threads.

Dynamics of lockstitch sewing process

During high speed sewing, the needle thread is exposed to dynamic loading, short strike loading, inertia forces, friction, rubbing, force of check spring, bending, pressure, friction, impact, shock and thermal influence. The dynamic thread loading/tension alters throughout the stitch formation cycle and along its passage through the machine. The greatest tensile force occurs at the moment of stitch stretching, when the take up lever pulls for required thread length through the tension regulator. These stresses act on the thread repeatedly and the thread passes 50-80 times through the fabric, the needle eye and the bobbin case mechanism, before getting incorporated into the seam, which result in upto 40% loss in tensile strength of the sewing thread. This damage in the sewing thread adversely affects its processing and functional performance. In this paper, the contribution of dynamic loading, passage through needle and fabric, and bobbin thread interaction in the loss in tensile properties has been studied. It is observed that the loss in tensile properties occurs mainly due to the bobbin thread interaction. Dynamic loading due to the action of take up lever also causes substantial loss in tenacity and breaking elongation of cotton threads.

EXPLORING THE FACTORS DRIVING OPINION POLARIZATION IN ONLINE GROUP DISCUSSIONS: AN INVESTIGATION OF VIRTUAL INVESTMENT-RELATED COMMUNITIES

ABSTRACT This study investigates the driving factors of opinion polarization, the phenomenon that individual opinions within a group discussion diverge to extreme positions, in the setting of virtual investment-related communities such as stock message boards. In this paper, I propose two factors – group size and discussion thread length – to introduce the main theories for the formation of polarization, social comparison theory (SCT) and persuasive arguments theory (PAT) respectively, to virtual communities. Specifically, I examine the effects that group size and thread length have on opinion polarization, which is measured by the degree of divergence of forum participants’ sentiments. The findings suggest that group size has a significant positive effect on opinion polarization. The result of thread length, however, is mixed. The effect of thread length on opinion polarization depends on the degree of posting activity on the message board. The analysis and findings contribute to prior literature, in which SCT and PAT were claimed to serve as two key determinants of opinion polarization, with an exploration in the context of virtual communities. Keywords Virtual communities, polarization, social comparison, persuasive arguments, computer-mediated communication

Experimental Study on the Mechanical Property of Visual Bolt-Ball Joint System

Grid structures with bolted spherical joints suffer impairment because of the “fake tightened-up” phenomenon. To prevent the “fake tightened-up” phenomenon, this study presents a new type of visual bolt-ball joint system that visually and effectively estimates the length of threads inserted into the bolt hole after adjusting the position of the fixed trip bolt and the location of the chute. The ultimate bearing capacity of the high-strength bolt and sleeve are studied via experiments. Results show that the failure section of high-strength bolts is the inclined section, which has a 60° angle to the direction of the screw, and a formula for calculating the ultimate bearing capacity is derived. Sleeves are compressed as their bearing failure is strength failure, which is due to yielding of the net section. A design method of the visual bolt-ball joint system is put forward according to the experimental results, and the safety of the visual bolt-ball joint is verified. Finally, the ductility and the fatigue performance of the visual bolt-ball joint are discussed in the paper.

Text classification for assisting moderators in online health communities

ObjectivesPatients increasingly visit online health communities to get help on managing health. The large scale of these online communities makes it impossible for the moderators to engage in all conversations; yet, some conversations need their expertise. Our work explores low-cost text classification methods to this new domain of determining whether a thread in an online health forum needs moderators’ help. MethodsWe employed a binary classifier on WebMD’s online diabetes community data. To train the classifier, we considered three feature types: (1) word unigram, (2) sentiment analysis features, and (3) thread length. We applied feature selection methods based on χ2 statistics and under sampling to account for unbalanced data. We then performed a qualitative error analysis to investigate the appropriateness of the gold standard. ResultsUsing sentiment analysis features, feature selection methods, and balanced training data increased the AUC value up to 0.75 and the F1-score up to 0.54 compared to the baseline of using word unigrams with no feature selection methods on unbalanced data (0.65 AUC and 0.40 F1-score). The error analysis uncovered additional reasons for why moderators respond to patients’ posts. DiscussionWe showed how feature selection methods and balanced training data can improve the overall classification performance. We present implications of weighing precision versus recall for assisting moderators of online health communities. Our error analysis uncovered social, legal, and ethical issues around addressing community members’ needs. We also note challenges in producing a gold standard, and discuss potential solutions for addressing these challenges. ConclusionSocial media environments provide popular venues in which patients gain health-related information. Our work contributes to understanding scalable solutions for providing moderators’ expertise in these large-scale, social media environments.

Imperfections in perfect architecture: The orb web of spiders

Among animal constructions, the orb webs of spiders are perfect geometrical architectural models. Webs are constructed by means of a succession of behaviours, which are often considered as instinctive and stereotyped. Anomalies in web structure are considered to be a consequence of variability in behaviour. In order to assess the variability in web structure, the spider Zygiella x-notata was allowed to build webs in the laboratory under standardized conditions. Webs (n = 127) were examined for anomalies, which were defined as modifications in the geometrical structure. Ten anomalies in the structure of webs produced by females, aged from 16 to 21 days after their adult moult, are described. The frequency of anomalies per web varies from 5 to 98. A very low percentage of the spiral elements of a web (less than 5%) were affected. Anomalies in the radii were less numerous (mean = 3 ± 3) than those in the sticky spiral (mean = 21 ± 11). Anomalies in the sticky spiral were different and more frequent in the peripheral than central parts of the webs. They were also relatively more numerous in the upper than in the lower part of the webs. Total number of anomalies was positively correlated with particular web characteristics (capture area, length of capture thread, width of the lower part of the web and mean distance between two spiral turns in the lower part) but not to the physical characteristics of the spiders (mass and size). Our results indicate that the orb webs of spiders, which are considered to be perfect geometrical structures, include anomalies mainly in the structure of the sticky spiral. These anomalies were the result of variability in behaviour during web building. In conclusion, their identification and description enable one to use them in spider webs as an index of behavioural variability.

Clinical efficacy of svarnkshiri tail pichu with ksharsutra in the management of bhagandara

Bhagandara i.e. Fistula in ano is one of the Asthomahagadha Vyadhi described by Sushruta which is difficult regarding its management. Fistula in Ano is disease of Ano rectum which characterised in humans by single or multiple sinuses with purulent discharge in the perianal region.The disease has been described in Sushrut Samhita and another Samhitas. Though it is a one of the Asthomahagadha Vyadhi the medical profession therefore has always been on the alert to devise and provide procedures and methods surgical or otherwise which could control disease effectively.The present study has been carried out to study the clinical efficacy of Svarnkshiri Tail Pichu with Ksharsutra in the management of Bhagandara was aimed to observe the efficacy of trial drug in Bhagandara .The clinical study was conducted on 60 patients selected randomly and divided into 2 groups based on the drug for the clinical trial. First group was treated with Ksharsutra with local application of Swarnkshiri Tail Pichu .Second group was treated with Ksharsutra only as controlled group.The clinical assessment was done on the basis of grading criteria with specific symptology of Bhagandara like Gudasrava, Gudashula, Gandha, Gudashotha and length of thread obtained at every sittings.Then mean scores levels of these symptoms before and after the treatment of 2 groups where subject for student paired 't' test for statistical analysis. The results were statistically and clinically significant not only to cure but also to prevent recurrence of the Bhagandara.

WE-F-105-03: Development of GPMC V2.0, a GPU-Based Monte Carlo Dose Calculation Package for Proton Radiotherapy

Purpose: Monte Carlo (MC) simulation is considered the most accurate method for proton therapy dose calculations. To improve its efficiency, we have previously developed a MC proton dose calculation package, gPMC, on a graphics‐processing unit (GPU) platform. This abstract reports our recent progress towards developing a new version gPMC v2.0, which aims at improving its clinical usability and evaluating it using proton therapy treatment plans. Methods: gPMC v2.0 supports loading source particles from a phase space file. Source particles are first placed to different energy bins according to their energies. Simulation is conducted to transport particles in each bin sequentially. This enforces that particles transported at the same time have similar energies and hence similar computational thread lengths, ensuring computational efficiency in parallel processing. Realistic treatment geometry is supported. A multi‐dose‐counter technique is developed, where multiple dose counters are allocated. Each dose deposition event is randomly assigned to one of the counters. This alleviates memory‐writing conflict problem, when multiple threads attempts to deposit dose to the same voxel. The final dose distribution and statistical uncertainty are obtained based on results at those counters. gPMC v2.0 also supports scoring dose‐to‐water. We have tested the new version in head‐and‐neck patient cases. Results: Computation time is ∼5 seconds for a typical patient case, where 2.1 million protons in a phase space file are simulated. It takes additional ∼8 seconds to load the phase space file. The dose distribution agrees well with that from TOPAS/Geant4. Inside a region of interest defined by the 50% iso‐dose line, gamma passing rate is ∼98% (3mm/3%) and ∼95% (2mm/2%) compared with TOPAS/Geant4 Result. The average relative uncertainty is 1.1%. Conclusion: gPMC has achieved accuracy and efficiency well beyond what was previously accomplished. It supports the recalculation of proton therapy treatment plans, making it feasible for routine clinical applications. This work is supported in part by the University of California Lab Fees Research Program and in part by R01 CA140735

Assessment of damping capacity as an index of root proximity in self-drilling orthodontic mini-implants

This study aims to investigate orthodontic mini-implant root proximity, placement torque, and damping capacity and to determine whether placement torque and damping capacity (Periotest value (PTV)) are useful indices for the estimation of mini-implant root proximity. The root proximity of 143 orthodontic mini-implants (1.6mm diameter, 8mm screw thread length) was evaluated in 79 patients (24 males, 55 females; mean age, 22.5 ± 8years) using cone-beam computed tomography. The placement torque and PTV of each implant were determined using a torque tester and the Periotest, respectively. Variability in these values according to root proximity was evaluated. PTVs of mini-implants with multiple (two or more) points of contact between the root and implant were significantly larger than those of mini-implants with no root contact in the self-drilling group. Placement torque did not differ significantly according to root proximity. In the self-drilling group, the odds ratio for root contact was 20.82 (P = 0.000) for a PTV >6. Placement torque could not be used to estimate root proximity. The PTV was significantly affected by root proximity in the self-drilling group. A threshold of PTV >6 could be applied clinically for the estimation of self-drilling mini-implant root proximity.

C-reactive protein a better indicator of inflammation after third molar extraction

The purpose of this study was to evaluate the relation between pre-operative pain and pre-operative levels of C-reactive and post-operative pain and swelling in impacted third molar surgery. In this prospective study subjects were patients indicated for mandibular third molar extraction. Patients were assessed for certain inclusion and exclusion criteria's. A standard surgical extraction procedure was followed to reduce the bias. Hematological investigation of C-reactive protein levels were recorded pre-operatively and post-operatively. Pain, swelling and trismus in patients were assessed pre-operatively and post-operatively in an interval of 24 hours, 48 hours and 7 days. Pain and swelling were measured using verbal analogue scale and thread length measurement respectively. The mouth opening was recorded, too. Post-operative C-reactive protein levels were seen consistency raised in those cases which showed high pre-operative levels. Peak levels of C-reactive protein were seen at 48 hours post operatively. It was observed that pre-operative pain swelling and mouth opening were seen to be variable in all the cases having high C-reactive protein levels. C-reactive protein was found to be a better indicator of inflammation than pre-operative pain, swelling and mouth opening for post-operative discomfort.

Web-Building Flexibility Differs in Two Spatially Constrained Orb Spiders

Shelter and trap-building animals that compete for limited space and/or face costly relocations benefit from being flexible in their construction behavior. Orb spiders are good examples of this and their easily quantifiable two-dimensional webs allow us to analyze the behavioral adaptations and costs in terms of higher error levels or less precision resulting from building webs in sub-optimal conditions. Here I study behavioral flexibility in spatially constrained spiders by analyzing a wide range of web parameters including measures that indicate errors during web-building. I compare the geometry of laboratory webs of two orb spiders, Cyclosa caroli and Eustala illicita, built in differently shaped experimental frames and report two major findings. i) The two species differ in their ability to build webs in constrained spaces. ii) E. illicita adjusted a range of parameters including shape, area utilization and mesh height in response to spatial constraints, but kept other parameters constant, most notably the length of anchor threads and the shape of the auxiliary spiral. I furthermore found that constrained spiders did not make significantly more errors during web-building than when they had amble space available.

Parameters of lengthened sacroiliac screw fixation: a radiological anatomy study

To provide the anatomical basis for the feasibility and clinical practice of lengthened sacroiliac screw fixation, by measuring various related indicators of the safe insertion regions of S1 and S2 lengthened sacroiliac screws. A total of 66 healthy pelvises of adults were scanned by 64-slice spiral CT and the length, width and height of the safe insertion regions for S1 and S2 lengthened sacroiliac screw were measured. The safe screw entrance point locations were described with a quantitative method. The indicators were recorded by descriptive statistics and the statistics of left and right sides, segments of S1 and S2, and different layers (including top, middle and bottom parts) of S1 and S2 were compared. The lengths of ilium within the safe insertion regions for lengthened screws are more than 16 mm. The width and height of the safe insertion region of S1 and S2 are almost all more than 7.3 mm. Generally, the width and height of S1 are larger than those of S2. The reference ranges of the best/safest entrance point locations of lengthened sacroiliac screws are as follows-S1: 42.21-63.69 mm in front of posterior superior iliac spine, 32.77-53.75 mm above the highest point of the greater sciatic notch; S2: 22.68-54.28 mm in front of posterior superior iliac spine, 14.06-33.70 mm above the highest point of the greater sciatic notch. (1) There is anatomical feasibility for the placements of S1 and S2 lengthened sacroiliac screws. (2) φ 7.3-mm partial thread cannulated screw (thread length 16 mm) and φ 6.5-mm partial thread cancellous screw(thread length 16 mm) can be used as lengthened sacroiliac lag screw. (3) The safe insertion space of S1 is larger than that of S2. (4) There is safe space for placement of at least one piece of lengthened sacroiliac screw in both S1 and S2. (5) The best/safest entrance points of S1 and S2 can be approximately located with anatomical landmarks.

BASIC DESIGN CRITERIA OF EXPELLING MACHINE FOR EXTRACTING WHEAT GERM OIL

An expelling machine for extracting wheat germ oil was designed and fabricated. The study included the investigation of the design criteria relating to hopper dimension and screw shaft parameters (outer diameter, pitch, thread depth, thread width, thread length, lead, lead angle, tapered angle, and number of turns on the screw shaft). The expelling machine was tested and evaluated at five screw speeds (25, 35, 45, 55, and 65 rpm) and four levels of press head clearance (0.5, 1, 1.5, and 2 mm) to determine the best machine capacity; percentage of oil recovery; percentage of residual oil; and specific energy consumption. The results showed that, the maximum machine capacity was 39 kg/h of raw material at 2mm outlet clearances, and 65 rpm of screw speed. The best operating pressing conditions for the wheat germ oil recovery was 45.7% at the 25 rpm of screw speed and 0.5 mm press head clearance, when the required specific energy was 0.0232 kWh/kgfeed.

Effects of thread depth, taper shape, and taper length on the mechanical properties of mini-implants

The primary stability of a mini-implant is critical, since most orthodontic mini-implant failures occur at an early stage. As orthodontic mini-implants have restrictions in diameter and length, an optimal design of the shape is important for sufficient primary stability. The purpose of this study was to investigate the influence of various mini-implants design factors, including thread depth, degree of taper, and taper length on insertion torque, pullout strength, stiffness, and screw displacement before failure. Finite element analyses were conducted first for identification of optimal design parameters. Four types of mini-implants with different design parameters were then custom manufactured and tested mechanically. All mechanical tests were performed in artificial bone with homogenous density to remove the variability associated with bone. Finite element results showed that, for mini-implants with a fixed external diameter of 2 mm, a thread length of 9.82 mm, and a pitch of 0.75 mm, those with greater thread depths, smaller taper degrees, and shorter taper lengths generated higher maximum stresses on the bone and thread elements. These mini-implants also had larger relative displacements. Maximum pullout resistance was attained with a core/external diameter ratio of 0.68. All mechanical results were compatible with the findings in the finite element analyses. Modification of the mini-implant design can substantially affect the mechanical properties. The finite element method is an effective tool to identify optimal design parameters and allow for improved mini-implant designs.