Short Stroke Research Articles

Force and deformation transmission characteristics of a compliant tendon-sheath actuation system based on Hill-type muscle model.

Artificial muscle is a kind of transmission actuator widely used in rehabilitation robots and wearable devices. However, there are some restrictions on the usage of these artificial muscles, including the short stroke length, complex structure, special power sources, and high nonlinear characteristics. Inspired by Hill-type muscle model, in this article, a new kind of artificial muscle using tendon-sheath and compliant springs is proposed to perform muscle-like characteristics. Force and deformation transmission models are proposed and validated by simulations and experiments. The experimental and simulation output results show nice goodness-of-fit and the R-square values are 0.9876 and 0.9046, respectively. Moreover, experiments are carried out in groups to analyze the transmission characteristics using different parameters, including variations of series springs, velocities, tendon diameters, and bending angles. The best R-square value of force-elongation curve and fitness curve could reach 0.9845, which indicates that the transmission model of the compliant artificial muscle can be used to express the transmission characteristics of the skeleton muscles.

Oral health care tips for caregivers

Oral health care is important for everyone, but some people may not be able to provide this care for themselves. Brushing gently with a soft-bristled toothbrush and fluoride toothpaste twice daily and cleaning between teeth daily is the general rule, but some people may be challenged by this routine. Here are some tips for helping others who have trouble with oral self-care. Some people may need only to be talked to or shown how to brush and clean between their teeth. Others might need you to take care of their oral hygiene completely. You may need to adapt the standard routine on the basis of the individual needs of the person you are helping. For example, some people may find it difficult to hold or use a traditional toothbrush. They might do better with a powered toothbrush. For someone who has trouble rinsing or has swallowing problems, try using a toothbrush moistened only with water.1National Institute of Dental and Craniofacial ResearchPractical oral care for people with disabilities: dental care every day—a caregiver's guide.https://www.nidcr.nih.gov/sites/default/files/2017-09/dental-care-every-day-caregiver.pdfDate accessed: March 6, 2019Google Scholar And although cleaning between teeth may be challenging, there are a number of “interdental cleaners” that may make this task easier such as prethreaded flossers, tiny brushes that reach between the teeth, water flossers, and wooden plaque removers, as well as dental floss. Here are some tips for providing hands-on care1National Institute of Dental and Craniofacial ResearchPractical oral care for people with disabilities: dental care every day—a caregiver's guide.https://www.nidcr.nih.gov/sites/default/files/2017-09/dental-care-every-day-caregiver.pdfDate accessed: March 6, 2019Google Scholar, 2American Dental Association The caregiver’s guide to dental health.https://www.mouthhealthy.org/en/adults-over-60/caregivers-guideDate accessed: March 6, 2019Google Scholar:▪The National Institute for Dental and Craniofacial Research suggests trying a “tell-show-do” approach: Tell the person how you’ll help him or her brush and what it might feel like. Show how you’re going to do each step before you do it. Do the steps in the same way that you’ve explained them.▪Before you begin, prepare the work area. You don’t necessarily have to use the bathroom for this activity. Set up wherever you and the person you’re caring for will be comfortable. Have all the things you’ll need within easy reach: toothpaste, a toothbrush, an interdental cleaner, a glass of water, and a bowl to spit into.▪Have the person sit up (or raise the head of the bed), and drape a towel over his or her chest.▪Wash your hands and put on disposable gloves.▪When you are ready, place a pea-sized amount of toothpaste on the moistened brush and brush each tooth surface, using short (toothwide) strokes.▪Help the person you are working with rinse with plain water, if possible. If there’s a risk of choking, such as a swallowing problem, you can swab the mouth gently with moistened gauze or a soft cloth.▪Clean between all teeth that touch, using an interdental product as directed.▪The dentist may recommend an oral rinse. If so, have the person you care for swish and spit the rinse out, as directed by the dentist. People who wear dentures need daily oral care, too. Dentures should be cleaned twice a day and stored in a cup of water when they are not being worn. Any removable full or partial dentures should be taken out before sleeping. Talk to your dentist or dental hygienist about the best way to care for dentures and how best to clean the mouth of the person you’re caring for. Regular visits with a dentist are key to oral health. The dentist can look for signs of tooth decay, gum disease, or oral cancer. Dental visits also are important for denture wearers. In addition to making sure the denture is fitting properly, the dentist can check for oral diseases like thrush. People with diseases associated with dementia, like Parkinson or Alzheimer’s, might consider seeing their dentist soon after diagnosis.3Alzheimer's AssociationDental care.https://alz.org/help-support/caregiving/daily-care/dental-careDate accessed: March 6, 2019Google Scholar Sitting still for dental treatments might become more difficult as the disease progresses. Providing dental care for another may present challenges, but with time and help from a dentist, you should be able to develop a routine that works for you and the person you care for.

Characterization of Performance of Short Stroke Engines with Valve Timing for Blended Bioethanol Internal Combustion

The present study provides a feasible strategy for minimizing automotive CO2 emissions by coupling the principle of the Atkinson cycle with the use of bioethanol fuel. Motor cycles and scooters have a stroke to bore ratio of less than unity, which allows higher speeds. The expansion to compression ratio (ECR) of these engines can be altered by tuning the opening time of the intake and exhaust valves. The effect of ECR on fuel consumption and the feasibility of ethanol fuels are still not clear, especially for short stroke engines. Hence, in this study, the valve timing of a short stroke engine was tuned in order to explore potential bioethanol applications. The effect of valve timing on engine performance was theoretically and experimentally investigated. In addition, the application of ethanol/gasoline blended fuels, E3, E20, E50, and E85, were examined. The results show that consumption, as well as engine performance of short stroke motorcycle engines, can be improved by correctly setting the valve controls. In addition, ethanol/gasoline blended fuel can be used up to a composition of 20% without engine modification. The ignition time needs to be adjusted in fuel with higher compositions of blended ethanol. The fuel economy of a short stroke engine cannot be sharply improved using an Atkinson cycle, but CO2 emissions can be reduced using ethanol/gasoline blended fuel. The present study demonstrates the effect of ECR on the performance of short stroke engines, and explores the feasibility of applying ethanol/gasoline blended fuel to it.

Interactive Contour Extraction via Sketch-Alike Dense-Validation Optimization

We propose an interactive contour extraction method inspired by a skill often adopted in sketching: an artist usually sketches an object by first drawing lots of short, directional, and redundant strokes, then following these small strokes to draw the final outline of the object. Our method simulates this process. To extract a contour, our method relies on user interaction, which provides us with a narrow band containing the target contour. Then, we densely sample sub-bands from the whole band, with each sub-band containing a local segment of the target contour. We design a curve-centered coordinate system in which a dynamic programming algorithm is proposed to extract the local segment in each sub-band. The local segment is guaranteed to be as evident and smooth as possible, to mimic the strokes sketched by the artist. Finally, we integrate all local segments of all sub-bands together to obtain the whole target contour based on the weighted principal component analysis. Our method can extract high-quality object contours due to the dense validations among local segments. That is, even if one segment deviates from the right location, several other segments in its local neighborhood can correct it in the integration stage. Both quantitative experiments and a user study demonstrate the effectiveness of the proposed method.

Parametric analysis of a dual-piston type free-piston gasoline engine linear generator

Abstract The free-piston gasoline engine linear generator (FPELG) is linear type power device, which couples a linear internal combustion engine and a linear electrical generator together. Free-piston gasoline engine is commonly modeled using simplified zero-dimensional models. In this paper, parametric analysis of a dual-piston type FPELG is presented, aiming to find the piston operation characteristics and the performances of the FPELG during the generating process. Model validation was undertaken with the test data from a running prototype, which showed good agreement. The results show that with fixed stroke, lower moving mass would lead to higher indicated power. With fixed moving mass, shorter stroke would make higher indicated power. The FPELG was observed to be operated at high load, and it was prone to operate at relative low speed. The influence of combustion parameters, i.e. the ignition timing and the combustion efficiency to the FPELG engine performance were also investigated respectively.

Abstract TP86: Matching CT Perfusion Deficit Very Early in the Time Window Seriously Overestimates Eventual Infarct Size With Prompt and Successful Endovascular Therapy

Introduction: There is an ongoing debate about the value of CT perfusion (CTP) in general, but especially in the short time window stroke cases. We decided to retrospectively review those cases where the stroke was witnessed so the patient got to the hospital very quickly, underwent CTP imaging, and after undergoing successful endovascular therapy (EVT), an MRI scan was done to confirm eventual completed stroke indicated by DWI changes. Hypothesis: CTP provides false information on irreversibility in such early stroke cases. Methods: A total of 125 EVTs for acute stroke were performed between 1/1/2016 and 8/10/2018. Of those 18 (14.4%) had event to reperfusion time equal or shorter than 2 hours. Four patients were treated without CTP imaging, so CTP data were available for 14 patients. The volume of irreversible stroke was calculated by the Philips ISP system using a CBV threshold of less than 2 ml per 100 grams of brain tissue. All of those 14 cases underwent successful EVT with TICI-2B or TICI-3 results. The volume of completed stroke after EVT was calculated from DWI images. We calculated a ratio of (CTP-DWI)/CTP volume. If the ratio = 0 then CTP is a good predictor. If the ratio is a positive number, CTP overestimates, if negative, it underestimates irreversible stroke volume. Results: The mean, median and SD of CTP was 36.2 ml, 17.4 ml and 50.0 ml, respectively, the same values for DWI changes were 10.05 ml, 2 ml and 15.37 ml. The median of the (CTP-DWI)/CTP ratio was 0.72 of all 14 cases, while in those 7 cases where the irreversible volume was predicted higher than 20 ml, the ratio remained 0.72. Discussion: CTP seriously overestimated final stroke volume in this group of patients. CTP provides prediction based on an arbitrary blood volume threshold (less than 2 ml/100 g tissue) which does not take into consideration time passed since the event. In this short retrospective analysis we found that within the hyper-acute phase of stroke CTP is unreliable. It shouldn’t be used to determine eligibility for EVT. On the other hand, spending 3 minutes on CTP was felt beneficial because it served as a physiologic confirmation of the anatomical CTA finding, as well as a predictor of expectable damage if the procedure would fail or not being done.

Abstract TP177: The Concept of Interdisciplinary Stroke Clinic With Physical Therapy: A Single Institution Experience

Background: Stroke survivors need therapy services to recover; however, coordination of therapy may not occur over time. An interdisciplinary stroke clinic (ISC) can improve communication and identify patients who have not reached their full recovery potential. We instituted an ISC with physical therapy (PT) to evaluate post-stroke or TIA survivors on the same day of the stroke clinic visit to determine if patients needed additional therapy. Methods: Patients with diagnosis of stroke or TIA seen in the ISC from 05/17 - 05/18 were included. Based on recommendations from the American Physical Therapy Association and AHA/ASA, the PT evaluation included the Berg Balance Scale (BBS), Ten Meter Walk Test (10MWT), Six Minute Walk Test (6MWT), Short Form Stroke Impact Scale (SF-SIS) and assessment of the patient’s knowledge of stroke risk factors and prevention. The physical therapist determined if the patient met criteria for additional therapy. Results: Among 161 patients in the study, 84% were ischemic stroke, 12% hemorrhagic stroke, and 4% TIA. The mean age was 63±14 years and there were 56% women and 75% Whites. At the time of therapy evaluation, 38% of patients were in the acute phase of recovery (0-6 months) and 62% in chronic phase (>6 months) of recovery from stroke or TIA. BBS was performed in 86%, median score 50 (41-54); 6MWT in 81%, median percent impaired 27(11-46), comfortable 10MWT in 86%, median 0.93 (0.72-1.11)m/s; fast 10MWT in 83%, median 1.31 (0.96-1.60)m/s; SF-SIS in 86%, median 33 (28-38), and SF-SIS stroke recovery rating in 81%, median 80% (50-90). Follow-up services were recommended for 62% of patients - PT (53%), occupational therapy (20%), and speech therapy (9%). Follow-up therapy recommendations were not associated with type of stroke (p=0.80, 68% hemorrhagic stroke, 61% ischemic stroke, and 67% TIA) or when stroke/TIA occurred in the past [p=0.24, 68% among patients in acute phase and 59% among patients in chronic phase of recovery]. Conclusion: In our pilot study, there was a need for follow-up services in 62% of patients due to functional limitations as determined by PT evaluation. It included patients in acute and chronic phase of recovery. Frequent therapy assessments may be needed for stroke survivors to help reach their best recovery potential.

Finite element analysis of shape accuracy of billet cold-forged with stepwise ram motion

Influence of stepwise ram motion, one of practical ram motion controls of servo press, on shape and dimensional accuracies of forged billet was investigated in cold cup forging process by the finite element analysis. In the process with stepwise ram motion, the billet inserted in the container was forged by the punch with upper ram of press, and the punch was operated with repetition of advance and pause modes. Following four stages were analyzed; (i) forging, (ii) removal of the punch from the forged billet, (iii) ejection of the forged billet from the container by the knockout punch and (iv) air cooling of the forged billet. In the analysis, the shape and dimensional changes of the inner wall of the billet during the four stages were investigated with several stepwise ram motions under the same forging duration. It is found that repetition of the punch advance with short stroke reduces heterogeneity of the temperature and stress distributions, so that the shape and dimensional accuracies of the inner wall of the forged billet were improved. The results of the finite element analysis were confirmed to be qualitatively agreed with the results of forging experiment on a link-type servo press.

Dynamic flight stability of hovering mosquitoes

The flight of mosquitoes is unusual compared with many other insects, such as fruit-flies and honey bees: mosquitoes fly with their legs spread; they also have rather short stroke amplitude, hence use different aerodynamic mechanisms to produce lift. Could their flight-stability properties be different from those of other insects? Here, we first measured wing kinematics and morphological parameters of two hovering mosquitoes, and then use the method of computational fluid dynamics to compute the aerodynamic derivatives and the techniques of eigenvalue and eigenvector analysis to study their stability properties. We found that their natural-mode structure is the same as that of many other insects: for the longitudinal motion, one unstable oscillatory mode, one stable fast subsidence mode and one stable slow subsidence mode; for the lateral motion: an unstable divergence mode, a stable oscillatory mode and a stable subsidence mode. The different aerodynamic mechanisms of mosquitoes do not change the major aerodynamic derivatives. The spread legs of mosquitoes have great effect on the moments of inertia and make the eigenvalue of the stable lateral mode much smaller. However, the leg-spreading has only a small quantitative effect on the unstable eigenvalues: the magnitudes of the eigenvalues in the two unstable modes, or the growth rate of the disturbances, are reduced by approximately 11%, compared to those calculated without considering the spread legs.

Design and Experimental Analysis of a 3 kW Single-Phase Linear Permanent Magnet Generator for Stirling Engines

A design method and load evaluation system for a single-phase linear permanent magnet generator (SPLPMG) for Stirling engines are proposed. The generator was designed considering the short stroke of the system and the characteristics of high-speed reciprocating motion. The accuracy of the 2-D finite-element method (FEM) was improved by considering the outer core and inner core split lamination characteristics. A test rig for evaluating the SPLPMG was fabricated. The evaluation system consisted of a crankshaft that converted the rotational motion into reciprocating motion, so that the linear generator could be evaluated as a rotational power source. The load test was carried out according to the operational frequency of the generator. An SPLPMG output of 3 kW was obtained, and the FEM analysis results and evaluation results were similar.

Reduction of Sticking in a Linear-Guideway Type Recirculating Ball Bearing

This paper deals with the reduction of sticking in a linear-guideway type recirculating ball bearing (linear bearing), which is the significant increase in the required driving force for a linear bearing in a back-and-forth short stroke operation. First, the driving force of a linear bearing with five carriage-body types (A–E, having different dimensions and shapes) under rolling moment load was measured. Simultaneously, the ball's position in the load zone was observed. The experimental results showed that regardless of the carriage-body types, the increasing rate of the driving force and the interspace (space between balls around the center of the load zone on the raised side) decreases and sticking tends to hardly occur as the maximum linear velocity and the stroke length increase. Also, the occurrence of sticking was affected by the carriage-body types. Finally, to examine the relationship of carriage-body types, carriage-body deformation, and the occurrence of sticking, the carriage-body deformation (caused by preloading and tightening torque of bolts) was calculated by finite element method (FEM). The FEM results showed that carriage-body type, which is more deformable, had a tendency to reduce sticking.

Relationship between short telomere length and stroke: A meta-analysis.

Background:Several epidemiological studies had been carried out in different population cohorts to estimate the relationship between the shortened telomere length and stroke. However, the results still remained dispute. Consequently, we conducted this meta-analysis to estimate the relationship between them.Methods:PubMed, EMBASE, and Web of Science were systematically searched for related articles to evaluate the association between “stroke” and “telomere length. STATA 12.0 software was used to perform the meta-analysis. The Cochran Q test and inconsistency index (I2) were used to assess the heterogeneity. Begg funnel plot and Egger test were used to assess publication bias.Results:The meta-analysis was composed of 11 studies, consisting of 25,340 participants. We found a significant relationship between shortened telomere length and stroke (OR: 1.50, 95% CI: 1.13–2.0; P = .005); however, in the prospective and retrospective study subgroup, we did not find a statistical significant relationship between shortened telomere length and stroke (the prospective subgroup: OR: 1.41, 95% CI: 1–1.98; P = .051) (the retrospective subgroup: OR: 1.89, 95% CI: 0.96–3.72; P = .067).

Association between sleep duration and stroke prevalence in Korean adults: a cross-sectional study

ObjectivesAlthough sleep, chronic disease and its related mortality are extensively studied areas, the association between stroke and sleep duration is relatively unknown. The aim of this study was to investigate...

Electrothermal Action of the Pulse of the Current of a Short Artificial-Lightning Stroke on Test Specimens of Wires and Cables of Electric Power Objects

The authors have given results of investigations of the electrothermal action of aperiodic pulses of temporal shape 10/350 μs of the current of a short artificial-lightning stroke on test specimens of electric wires and cables with copper and aluminum cores and sheaths with polyvinylchloride and polyethylene insulations of power circuits of industrial electric power objects. It has been shown that the thermal stability of such wires and cables is determined by the action integral of the indicated current pulse. The authors have found the maximum permissible and critical densities of this pulse in copper and aluminum current-carrying parts of the wires and cables. High-current experiments conducted under high-voltage laboratory conditions on a unique generator of 10/350 μs pulses of an artificial-lightning current with amplitude–time parameters normalized according to the existing requirements of international and national standards and with tolerances on them have confirmed the reliability of the proposed calculated estimate for thermal lightning resistance of cabling and wiring products.

Lean Burn Performance of a Spark Ignition Engine with an Ethanol–Gasoline Dual Injection System

A spark ignition (SI) engine with an ethanol direct injection (EDI) and gasoline port injection (GPI) system has been studied quite recently. In order to investigate its application, experiments were carried out on a single-cylinder 250 cm3 short stroke motorcycle SI engine, which is supplied with the ethanol–gasoline dual injection system. Experimental findings have revealed that EDI helped increase the lean combustion limit owing to the combination effects of the dual injection and ethanol fuel. At the identical engine speed and load, the lean burn limit in the dual injection model was, on average, 0.2 times higher than that in the corresponding single GPI model. Increasing ethanol energy ratio (EER) gave rise to the increase in the lean burn limit; nevertheless, the increase rate began reducing when the EER was above 48% and 42% at 4000 and 3500 rpm, correspondingly. Subsequently, late ethanol direct injection (LEDI), following the intake valve closing slightly extended the lean burn limit, probably, o...

Development of High‐Acceleration Linear Motor to Realize Resource Saving and High Productivity

SUMMARYThe use of linear motors has been rapidly increasing in recent years in response to the rising demand for drive mechanisms with higher speed and acceleration to improve the throughput of semiconductor production equipment, machine tools, and so on. In this study, we have developed a new type of linear motor with an opposed magnetic pole structure and twin movers. To achieve higher acceleration of a linear motor, it is necessary to satisfy both large thrust and low inertia. In our proposed new type linear motor, the thrust is improved by increasing the facing area between the permanent magnets and magnetic pole teeth by using multistage movers. Furthermore, the magnetic leakage flux is reduced by multiplexing the magnetic flux path. In a short stroke (approximately 210 mm) drive, the high acceleration of 1670 m/s2 and maximum velocity of 14.2 m/s is demonstrated using a prototype linear motor (maximum thrust = 25 kN).

Model‐Based Optimization of Short Stroke Control in Roughing Mills

Automatic width control is one key issue in hot strip rolling and the main actuator for width control is the vertical draft (edging) applied to slabs in the roughing sequence. In order to compensate for the occurring strip necking, a variable edger gap is applied in the edging process. This paper introduces a comprehensive mathematical optimization approach for the fully automatic generation of the associated edger roll trajectories, which is based on a nonlinear dynamic simulation model for the material flow in the roughing mill. Due to the complexity of this simulation model, gradient‐based methods are applied to solve the resulting optimization problem in reasonable time. Hence, derivatives of cost functional and constraints must be provided, which entails computing sensitivity information from the underlying simulation model. Finally, numerical results for real‐world examples are discussed to illustrate the capability of the presented approach. In particular, this paper examines the influence of characteristic parameters such as the slab width or the maximum edger screw in velocity onto the optimization results.

Effects of lateral harmonic vibrations on film thickness in EHL point contacts

Abstract Vibrations are an integral part of machine operation and affect every elastohydrodynamically lubricated conjunctions. In the present experimental study, a rolling contact is subjected to lateral-sliding vibrations with short stroke length. Film thickness behaviour is investigated under diverse conditions including rolling speeds, stroke lengths, frequencies, loads, and variety of lubricants. The results obtained under vibrations are compared with the results for corresponding steady state conditions to determine the effects of vibrations. It is shown that the lubricant rheology and the ratio of main and lateral entrainment speed are crucial parameters where the influence of this ratio on relative film thickness and its deviations can be estimated by exponential functions uniformly for all lubricants. The thresholds for film failures were found.

Engine Manifold Wave Action under Variable Stroke Length

A theoretical investigation on the pressure wave action of the manifolds of a four-stroke, direct injection (hereinafter referred to as DI), water-cooled, 4-stroke, diesel engine with variable stroke length was carried out. The study was conducted over wide range of speeds (1000 - 3000 RPM at an increment of 500 RPM) and stroke lengths (130 mm to 210 mm at an increment of 20mm). The compression ratio was kept constant by adjusting the piston bowl volume. The study showed that shorter stroke lengths created favorable pressure waves in both inlet and exhaust manifolds at lower speeds, which resulted in improved engine volumetric and thermal efficiencies. At higher speeds, the larger strokes were favorable, however, due to less time available for the suction and exhaust strokes to be executed, the efficiencies were low. Advancing valve timing was one factor that improved the engine performance with larger stroke lengths.

3-D Electromagnetic Analysis of Single-Phase Tubular Switched Reluctance Linear Launcher

A reciprocating single-phase tubular switched reluctance linear launcher (TSRLL) with a short stroke is presented in this paper. The parametric design of this launcher is achieved based on finite-element method (FEM). By using the finite-element (FE) software FLUX, the 2-D and 3-D electromagnetic analyses of this launcher are carried out, respectively. The characteristic curves of position-current-flux linkage are analyzed by the 2-D and 3-D FEM. The prototype tests are conducted to verify the FE analyses. The static tests results show that the 3-D FE calculated results are more precise than the 2-D FE calculated results, and they coincide well with prototype static test results. The effectiveness of the FE model for the TSRLL is further testified by the results of prototype dynamic tests. Finally, some analyses on sensitivity parameters are conducted to further improve the performance of the TSRLL.