Design and Control of Multi-Plate MR Clutch Featuring Friction and Magnetic Field Control Modes.

A magnetorheological (MR) multi-plate clutch was proposed with both mechanical friction mode and magnetic field control modes. The magnetic field control mode was based on an MR fluid coupler that changed its viscous properties according to the density of an applied magnetic field. This mode was used in the early stage of clutch operation to reduce the impact of friction between the disc and plate, and eliminate to the extent possible the difference in their relative speeds when contacting each other in later stages. Once the rotational speed difference between the disc and plate was reduced, the clutch was operated in mechanical friction mode by compressing the friction surfaces together. A torque modeling equation was then derived for each mode based on the Bingham model of the MR fluid, and the transmission torque of the proposed multi-plate clutch was derived using these equations as well as magnetic field analysis results obtained using ANSYS Maxwell. A multi-plate MR clutch was then fabricated, and its torque transmission characteristics were evaluated in the magnetic field control and mechanical friction modes. The results confirmed that the model-based torque calculations were consistent with the observed transmission torque. Finally, control algorithms for mechanical friction only and mixed mechanical friction/magnetic field control torque tracking of the proposed MR multi-plate clutch were designed, and their performances were evaluated when applying unit step command, half-sine-wave command, and rotational speed changes. The results indicated that the torque tracking control was performed smoothly, demonstrating the advantages of the proposed clutch.

Design and Analysis of a Hybrid Annular Radial Magnetorheological Damper for Semi-Active In-Wheel Motor Suspension.

In this study, a novel hybrid annular radial magnetorheological damper (HARMRD) is proposed to improve the ride comfort of an electric vehicle (EV) powered by an in-wheel motor (IWM). The model primarily comprises annular-radial ducts in series with permanent magnets. Mathematical models representing the governing motions are formulated, followed by finite element analysis of the HARMRD to investigate the distribution of the magnetic field density and intensity of the magnetorheological (MR) fluid in both the annular and radial ducts. The optimized model generates a damping force of 87.3-445.7 N at the off-state (zero input current) with the excitation velocity ranging between 0 and 0.25 m/s. By contrast, the generated damping force varies from 3386.4 N to 3753.9 N at an input current of 1.5 A with the same velocity range as the off state. The damping forces obtained using the proposed model are 31.4% and 19.2% higher for the off-field and on-field states, respectively, compared with those of the conventional annular radial MR damper. The efficiency of the proposed model is evaluated by adopting two different vehicles: a conventional vehicle powered by an engine and an EV powered by an IWM. The simulation results demonstrate that the proposed HARMRD along with the skyhook controller significantly improves both the ride comfort and road-holding capability for both types of vehicles.

Methodology for Sound Quality Analysis of Motors for Automotive Interior Parts through Subjective Evaluation.

With the development of autonomous vehicles, activities in the indoor spaces of autonomous vehicles are diversifying. Therefore, as the operating range of the interior parts increases, the occupant becomes sensitive to the operating noise of autonomous vehicles. Therefore, to reduce operating noise, it is necessary to analyze the causal relationship between the mechanical/electrical noise characteristics of the motor and sound quality. In this paper, we propose a methodology to analyze the relationship between the noise frequency components and the sound quality of small motors used in automobile interior parts. Two types of motors were selected for this study, and noise measurements and analyses were performed by applying the design proposed in this study. Subjective sound quality evaluations were conducted using the 12 pairs of adjectives extracted from the survey. The results suggest that subjective sound quality evaluation scores should be converted to Z-scores to ensure the reliability of the statistical analysis. In addition, we present a critical sound quality value that can be used as a criterion for determining whether the sound quality is positive (good quality) or negative (bad quality). Sound quality regression models explain the causal relationship between rotational frequency components of the motor and subjective sound quality characteristics. Thus, a method for analyzing the effect of the rotational frequency component of the motor on the sound quality is presented, which suggests that it can be used as basic research data to improve the noise performance of the motor.

A New Fracture Detection Algorithm of Low Amplitude Acoustic Emission Signal Based on Kalman Filter-Ripple Voltage.

In this study, an acoustic emission (AE) sensor was utilized to predict fractures that occur in a product during the sheet metal forming process. An AE activity was analyzed, presuming that AE occurs when plastic deformation and fracturing of metallic materials occur. For the analysis, a threshold voltage is set to distinguish the AE signal from the ripple voltage signal and noise. If the amplitude of the AE signal is small, it is difficult to distinguish the AE signal from the ripple voltage signal and the noise signal. Hence, there is a limitation in predicting fractures using the AE sensor. To overcome this limitation, the Kalman filter was used in this study to remove the ripple voltage signal and noise signal and then analyze the activity. However, it was difficult to filter out the ripple voltage signal using a conventional low-pass filter or Kalman filter because the ripple voltage signal is a high-frequency component governed by the switch-mode of the power supply. Therefore, a Kalman filter that has a low Kalman gain was designed to extract only the ripple voltage signal. Based on the KF-RV algorithm, the measured ripple voltage and noise signal were reduced by 97.3% on average. Subsequently, the AE signal was extracted appropriately using the difference between the measured value and the extracted ripple voltage signal. The activity of the extracted AE signal was analyzed using the ring-down count among various AE parameters to determine if there was a fracture in the test specimen.

Dynamic Analysis of Sphere-Like Iron Particles Based Magnetorheological Damper for Waveform-Generating Test System.

In this study, a new double pulse waveform-generating test system with an integrated magnetorheological (MR) damper is proposed. Since the total shear stress of MR fluid can be varied according to the shape of particles, sphere-like iron particles-based MR fluid is filled into the MR damper. The test system consists of a velocity generator, three masses (impact, test, and dummy), a spring, and an MR damper. To tune the double pulse waveform profile, a damping force model is constructed to determine the fundamental parameters of the simulator. Then, the first and second shock waveform profiles are analyzed to solve the governing equation of motions representing the damping force and velocity. The mathematical model of the MR damper is formulated and applied to a simulator with a graphical user interface programmed using MATLAB. The effectiveness of the proposed simulator-featuring controllable MR damper is demonstrated by comparing the simulation and experimental results.

Evaluation of the Ejection Pressure for Tracking Internal Cracks during Compaction in Bilayer Tablet Formulations Using Experimental and Finite Element Methods.

This study aimed to evaluate the ejection pressure and the correlation of the findings with the occurrence of internal cracks within bilayer tablets (BLTs) consisting of metformin HCl (MF) and evogliptin tartrate (EG). Then, the mechanism of tablet failure was provided by the finite element method (FEM). The ejection pressure and the difference in diameter depending on MAIN-P were evaluated to understand the correlation between ejection pressure and change in the BLT internal structure. The ejection pressure and the difference in diameter increased as the MAIN-P increased, then steeply decreased from 350 MPa to 375 MPa of MAIN-P, despite there being no pattern in compaction breaking force and porosity. The mechanical integrity at the BLT interface was weakened by internal cracks, reducing ejection pressure. The stress distribution analysis during the compression revealed that crack formation caused by entrapped air located at the center of the BLT interface may not propagate due to concentrated stress, which promotes a tight bond at the edge of the BLT. Furthermore, complete delamination can occur in the ejection process due to localized and intensive shear stresses at the BLT interface. These findings indicate that the mechanisms of internal cracking and delamination were successfully confirmed by FEM simulation. Moreover, measuring ejection pressure before BLT manufacturing can prevent invisible tablet cracks without damaging the tablets.

Epidemiology and clinical characteristics of trauma in older patients transferred from long-term care hospitals to emergency departments: A nationwide retrospective study in South Korea.

BACKGROUND: South Korea's aging population had leg to an increased number of long-term care hospitals (LTCHs), and increased transfer of older patients to emergency departments (EDs). This study investigated the epidemiological and injury profiles of LTCH patients aged ≥65 who were transferred from LTCHs to EDs due to trauma. METHOD: This retrospective study conducted between January 2014 and December 2019 in South Korea utilized data from the National Emergency Department Information System. The requirement for informed consent was waived by the IRB due to the retrospective nature of the study. Patient information was anonymized prior to analysis. RESULTS: Of the 1,472,006 trauma cases aged ≥65, 14,469 came from LTCHs. Outcomes varied: 44.1% were discharged, 40.6% were admitted to general wards (GW), 5.9% to intensive care units (ICU), 2.4% to other hospitals, and 6.5% returned to LTCHs. ED length of stay (LOS) was longest in the death (410.28 ± 559.73 min) and GW admission (390.12 ± 621.71 min) groups. Falls were the main cause of injury (50.1%), and the most common fracture was femoral (71.6%). Femoral and shoulder/upper extremity fractures increased hospitalization risk only, whereas self-harm increased both hospitalization and mortality risk. CONCLUSION: Visits to the ED by older patients from LTCH for trauma were avoidable in 50.6% of cases. Additionally, these patients had longer ED LOS and higher hospitalization rates than non-LTCH patients. Falls were the predominant mode of presentation, femoral fracture was the most common fracture among patients from LTCH.

Epidemiology and Clinical Characteristics of Older Patients Transferred from Long-Term-Care Hospitals (LTCHs) to Emergency Departments by a Comparison with Non-LTCHs in South Korea: A Cross-Sectional Observational Study.

The South Korean population is rapidly aging, and the number of older patients in long-term-care hospitals (LTCHs) continues to increase. This study aims to investigate the epidemiologic data, characteristics, and clinical outcomes of patients aged 65 years and older transferred from LTCHs to emergency departments (EDs). This is a retrospective study based on National Emergency Department Information System data from 2014 to 2019. Of the 6,209,695 older patients visiting EDs for disease treatment, 211,141 (3.4%) were transferred from LTCHs. Among patients from LTCHs (211,141), 24.2% were discharged from EDs, 43.0% were admitted to general wards, 20.7% were hospitalized in intensive care units, 3.1% were transferred to another hospital, 6.1% returned to LTCHs, and 2.1% died in EDs. ED stays were the longest for those returning to LTCHs (710.49 ± 1127.43 min). Foley catheterization (40.3%) was most frequently performed in preventable ED visits. In South Korea, older patients being discharged from the ED or returning to LTCHs, after being transferred from LTCHs to EDs, increased. ED stays among older LTCH patients were longer than among non-LTCH older patients, contributing to congestion. To reduce avoidable transfer to EDs from LTCHs, it is necessary to discuss policies, such as expanding appropriate medical personnel and transitional treatment.

Effect of Dietary Supplementation of Fermented Pine Needle Extract on Productive Performance, Egg Quality, and Serum Lipid Parameters in Laying Hens.

This study aimed to investigate the supplemental effects of fermented pine (Pinus densiflora) needle extract (FPNE) in laying hen diets on productive performance, egg quality, and serum lipid metabolites. A total of 108 40-week-old Hy-line brown laying hens were randomly assigned to one of the three dietary treatment groups: (1) basal diet + 0 mL FPNE/kg diet (CON), (2) basal diet + 2.5 mL FPNE/kg diet (T1), or (3) basal diet + 5 mL FPNE/kg diet (T2) for 6 weeks. Each group consisted of four replicates of nine hens each. Feed and water provided ad libitum. Results showed that dietary supplementation of FPNE increased egg production percentage (linear, p < 0.01 and quadratic, p < 0.05), egg mass (linear, p < 0.05), and feed intake (linear, p < 0.05) during the entire experimental period. In addition, dietary inclusion of FPNE significantly increased the eggshell color (linear, p < 0.01), egg yolk color (quadratic, p < 0.01), and eggshell breaking strength (linear, p < 0.05 and quadratic, p < 0.05) while the Haugh unit decreased (quadratic, p < 0.05). However, serum lipid profile did not differ among the dietary treatments (p > 0.05). Notably, antioxidant activity of egg yolk was improved by significantly decreasing the malondialdehyde content in egg yolks after 6 weeks of storage (linear, p < 0.001 and quadratic, p < 0.05). In summary, dietary inclusion of FPNE could improve laying performance and the antioxidant capacity of eggs.

Effect of dietary supplementation of a phytogenic blend containing Schisandra chinensis, Pinus densiflora, and Allium tuberosum on productivity, egg quality, and health parameters in laying hens.

OBJECTIVE: This study was conducted to investigate the supplementary effect of a phytogenic blend (SPA: a mixture containing fermented Schisandra chinensis pomace, fermented Pinus densiflora needle extract, and Allium tuberosum powder in the ratio of 2:2:1) on egg production, egg quality, blood constituents, and visceral organs in laying hens. METHODS: A total of 135 Hy-line brown laying hens (48-wk-old) were randomly allocated to three dietary treatments with 5 replicates of 9 hens. The control group (CON) was fed a basal diet (no exogenous SPA addition) and the experimental groups were fed the basal diet containing SPA at the level of 0.1% and 0.3% for 6 weeks. RESULTS: The feed intake was significantly improved in SPA supplemented groups as compared with the control (p<0.05). However, egg production, daily egg mass, and feed conversion ratio were not different among the dietary treatments (p>0.05). For egg quality traits, only Haugh unit (HU) was significantly improved in SPA (0.3%) (p<0.05) as compared with other groups. However, HU was not affected during 4-wk of storage at 18°C among the dietary treatments (p>0.05). Furthermore, SPA supplementation did not affect the blood biochemical constituents except for the phosphate content, which was significantly higher in SPA groups than the CON group (p<0.05). There were no significant differences in visceral organ characteristics and immune indicators (immunoglobulin A [IgA], IgG, and IgM) in SPA or CON groups. CONCLUSION: This study suggested that the supplementation of SPA may have beneficial effects on feed intake and egg quality in laying hens.

Biportal Endoscopic Spinal Surgery for Lumbar Spinal Stenosis.

Biportal endoscopic spinal surgery (BESS) is a minimally invasive spinal surgery, which is basically similar to microscopic spinal surgery in terms of the use of floating technique and technically similar to conventional percutaneous endoscopic spinal surgery in terms of the use of endoscopic or arthroscopic instruments. Using two independent portals (viewing and working) and maintaining a certain distance from the bony and neural structures allow closer access to the target lesion through a panoramic view by free handling of the scope and instruments rather than through a fixed view by docking into the Kambin's triangle. Minimally invasive surgery allows for reduced dissection and inevitable muscle injury, preserving stability and reducing risks of restabilization. The purpose of fusion surgery is the same as that of the three surgical techniques stated above. Its wider range of view helps to overcome limitations of conventional endoscopic spinal surgery and to supplement the weak points of microscopic spinal surgery, such as limited working space in a tubular retractor and difficulty in accessing the contralateral area. This technique provides an alternative to unilateral or bilateral decompression of lumbar central spinal stenosis, foraminal stenosis, low-grade spondylolisthesis, and adjacent segment degeneration. Early clinical outcomes are promising despite potential for complications, such as dural tearing and postoperative epidural hematoma, similar to other procedures. Merits of BESS include decreased postoperative infection rate due to continuous irrigation throughout the procedure and decreased need for fusion surgery for one- or two-level lumbar stenosis by wide sublaminar and foraminal decompression with minimal sacrifice of stabilizing structures.

Material Characterization of Hardening Soft Sponge Featuring MR Fluid and Application of 6-DOF MR Haptic Master for Robot-Assisted Surgery.

In this work, the material characterization of hardening magneto-rheological (MR) sponge is analyzed and a robot-assisted surgery system integrated with a 6-degrees-of-freedom (DOF) haptic master and slave root is constructed. As a first step, the viscoelastic property of MR sponge is experimentally analyzed. Based on the viscoelastic property and controllability, a MR sponge which can mimic the several reaction force characteristics of human-like organs is devised and manufactured. Secondly, a slave robot corresponding to the degree of the haptic master is manufactured and integrated with the master. In order to manipulate the robot motion by the master, the kinematic analysis of the master and slave robots is performed. Subsequently, a simple robot cutting surgery system which is manipulated by the haptic master and MR sponge is established. It is then demonstrated from this system that using both MR devices can provide more accurate cutting surgery than the case using the haptic master only.

Correlation between endobutton loop length and tunnel widening after hamstring anterior cruciate ligament reconstruction.

BACKGROUND: Previous reports have shown that graft fixation with the Endobutton is associated with tunnel widening because it provides distant fixation rather than aperture fixation. HYPOTHESIS: A longer loop of the Endobutton results in greater tunnel widening than a shorter loop. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 171 consecutive patients underwent hamstring anterior cruciate ligament (ACL) reconstruction fixed with the Endobutton. They were followed for a minimum of 2 years postoperatively. A 15-mm loop was used in 20 patients, a 20-mm loop in 53, a 25-mm loop in 58, and a >30-mm loop in 40. On anterior-posterior (AP) and lateral radiographs, the measured diameters of the femoral tunnel at 2 years after surgery were compared with the diameter of the reamer used at surgery. The measured diameter of the tibial tunnel at 2 years after surgery was compared with measurements taken on the immediate postoperative day. The center of the tibial tunnel and direction of the ACL graft were also measured. Postoperative knee stability was evaluated using the Lachman test, pivot-shift test, and KT-1000 arthrometer. Functional evaluations were performed using the Lysholm score and Tegner activity scale. All measurements were compared among the 4 groups according to the length of the Endobutton loop. RESULTS: The mean ± standard deviation (SD) diameter of the femoral tunnel increased by 50.7% ± 23.3% and 37.0% ± 18.8% on AP and lateral radiographs at 2 years after surgery, respectively. The mean ± SD diameter of the tibial tunnel increased by 40.8% ± 19.3% and 46.4% ± 22.6% on AP and lateral radiographs, respectively. No significant difference in tunnel widening was present according to the length of the Endobutton loop. There were no significant differences in the average center of the tibial tunnel or the average angle of the direction of the ACL graft among the 4 groups. There was no significant difference in Lachman test results, postoperative KT-1000 arthrometer side-to-side differences, Lysholm score, and Tegner activity scale score among the 4 groups. The group with a >30-mm loop showed a significant difference in the pivot-shift test than the other 3 groups (P = .023). CONCLUSION: A longer Endobutton loop did not result in greater tunnel widening than a shorter loop. Long fixation distance may not be associated with tunnel widening after hamstring ACL reconstructions.

All-inside repair for a root tear of the medial meniscus using a suture anchor.

BACKGROUND: There are no published articles reporting clinical outcomes after all-inside meniscal repair using a suture anchor for a medial meniscal root tear. PURPOSE: To evaluate the subjective and objective outcomes after repair of medial meniscal root tears. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Thirteen patients with a root tear of the medial meniscus underwent all-inside repair using a suture anchor. Postoperative evaluation of meniscal status was performed using physical examination criteria, specifically joint line tenderness, McMurray test, and follow-up magnetic resonance imaging (MRI). Functional evaluations were performed using Tegner activity level and Lysholm knee score. Follow-up MRI scans were obtained 6 months postoperatively to evaluate healing of the root tear and measure extrusion of the midbody of the medial meniscus. RESULTS: The average follow-up was 30.8 months (range, 24-40 months). No patients had joint line tenderness or effusion. No patients demonstrated a positive McMurray test result postoperatively. The preoperative mean Tegner activity level was 1.9 (range, 1-6), and the mean Lysholm score was 69.1 (range, 53-91). At last follow-up, the mean Tegner activity level was 3.9 (range, 2-6), and the mean Lysholm score was 90.3 (range, 75-100). Improvements in both the Tegner activity level and Lysholm score were statistically significant (P = .001 and P = .000, respectively). Follow-up MRI was performed in 10 patients. Five (50%) patients showed complete healing; 2 of these 5 patients showed complete healing with isointense signal of a normal meniscus, and 3 showed intermediate signal tissue at the previous tear site without any high signal cleft or ghost sign. Four (40%) patients showed partial healing, and 1 (10%) showed no healing. Mean extrusion of the midbody of the medial meniscus was 3.9 mm (range, 2.2-7.1 mm) preoperatively and 3.5 mm (range, 1.2-6.1 mm) postoperatively. Extrusion was not significantly decreased. CONCLUSION: This study demonstrated symptomatic improvement after meniscal root repair using a suture anchor. However, follow-up MRI scans did not show complete healing of all repaired root tears.

Application of pulsed corona induced plasma chemical process to an industrial incinerator.

Pulsed corona induced plasma chemical process (PPCP) has been investigated for the simultaneous removal of NO(x) (nitrogen oxides) and SO2 (sulfur dioxide) from the flue gas emission. It is one of the world's largest scales of PPCP for treating NO(x) and SO2 simultaneously. A PPCP unit equipped with an average 120 kW modulator has been installed and tested at an industrial incinerator with the gas flow rate of 42 000 m3/h. To improve the removal efficiency of SO2 and NO(x), ammonia (NH3) and propylene (C3H6) were used as chemical additives. It was observed that the pulsed corona induced plasma chemical process made significant NO(x) and SO2 conversion with reasonable electric power consumption. The ammonia injection was very effective in the enhancement of SO2 removal. NO removal efficiency was significantly improved by injecting a C3H6 additive. In the experiments, the removal efficiencies of SO2 and NO(x) were approximately 99 and 70%, respectively. The specific energy consumption during the normal operation was approximately 1.4 Wh/m3, and the nanopulse conversion efficiency of 64.3% was achieved with the pulsed corona induced plasma chemical process.