The Simulation Analysis and Experimental Study on the Temperature Field of Four Row Rolling Bearings of Rolling Mill under Non-Uniform Load Conditions

As a key component of the rolling mill, the four-row cylindrical roller bearing (FCRB) operates under complex working conditions of high speed, high temperature, and heavy load. Due to the lack of an effective temperature test scheme for rolling mill bearings, a too high temperature can easily lead to bearing failure or damage under unsteady conditions. To reveal the internal temperature distribution law of four-row roller bearings of rolling mills and solve the common problem of difficult temperature monitoring of rolling mill bearings, in this paper, a four-row cylindrical roller bearing of 1140 mm cold rolling six-high mill is taken as the research object, and the temperature field calculation model for four-row cylindrical roller bearings is established. Firstly, the mechanical analysis model of FCRB is established on the basis of single row bearing by slice method. Secondly, the mechanical calculation model of FCRB is established by the Newton-Raphson method (NRM) and the finite element method (FEM). Thirdly, based on the mechanical calculation model, the finite element method is used to establish the temperature field model of FCRB under uniform load distribution and non-uniform load distribution. Finally, the temperature test experiment is carried out with the FCRB in the rolling mill fault diagnosis test bench. The results show that the error between the FCRB temperature calculation model and the experimental results is less than 10%. It can be seen that the uneven temperature distribution of FCRB is mainly caused by the uneven load distribution. The temperature distribution along the axial direction of the bearing is related to the load distribution of each column, while the circumferential temperature distribution is related to the azimuth angle.

Force loss and distribution of load in the hands of patients with cubital tunnel syndrome

Manugraphy with three different cylinder sizes was used to quantify the contribution of fingers, thumb and palm to grip force in patients with unilateral cubital tunnel syndrome. Forces in the affected and contralateral hands differed by up to 29%. Although grip force is usually maximal when gripping small handles, ulnar nerve palsy resulted in similar absolute grip forces using the 100-mm and 200-mm cylinders. The contact area between the affected hand and the cylinders was reduced by 5%-9%. We noted a high correlation between the contact area and grip force, visible atrophy and permanently impaired sensibility. The load distribution differed significantly between both hands for all cylinder sizes. When gripping large objects, the main functional impairment in cubital tunnel syndrome is weakness in positioning and stabilizing the thumb. Weak intrinsic finger muscles are responsible for loss of force when gripping small objects. Level of evidence: III.

Load Distribution in Dorsally-Angulated Distal Radius Deformity Using Finite Element Analysis

PURPOSE

The load axis of the carpals is located on the volar side of the normal distal radius. A volar lunate facet fracture (VLFF) is exposed to volar-shearing stress, which can cause volar displacement of the carpus. A previous biomechanical study reported that the load at the scaphoid fossa was located more dorsally and the pressure at the lunate fossa decreased in a dorsally-angulated model. However, the distal radius load distribution for various volar tilts remains unclear. We speculate that if the volar tilt decreases, the load distribution moves dorsally and decreases the stress on the VLFF. Therefore, we analyzed a dorsally-angulated distal radius model to evaluate changes in the load distribution using finite element analysis.

METHODS

A 3-dimensional finite element wrist model was developed using computed tomography images. The ligaments were modeled as tension-only spring elements. We considered the intact wrist model for a volar tilt of 15° and created 5 additional models for volar tilts of 10°, 5°, 0°, -5°, and -10°.

RESULTS

As the dorsal angulation increased, the stress distribution moved from volar to dorsal and from the lunate fossa toward the scaphoid fossa. The maximum stress on the volar lunate facet was reduced as volar tilt decreased. The maximum stress was higher on the lunate fossa for volar tilts from 15° to 5°. In contrast, the maximum stress was higher on the scaphoid fossa for volar tilts of ≤0°.

CONCLUSIONS

Load transmission moved from volar to dorsal and from the lunate fossa to the scaphoid fossa when the volar tilt decreased. Therefore, a decrease in the volar tilt would reduce the load on the VLFF.

CLINICAL RELEVANCE

This study provides surgeons accurate knowledge regarding load distribution of the distal radius for various volar tilts that could be helpful in treating patients with VLFFs.

Load distribution structure of rear bumper beam to enhance vehicle body energy absorption in rear-end collisions

OBJECTIVE

This research focused on FMVSS301, which is required for higher energy absorption as a regulation for rear-end collisions. Since they are offset collisions, the deformation of the non-collision side frame, which does not directly contact the barrier, is less than on the collision side. The reason is that the rear bumper beam with curvature is deformed into a straight shape by the load from the barrier, resulting in an asymmetrical load distribution from the barrier that is biased toward the collision side. Therefore, the objective of this research was to construct a new bumper beam structure that reduces the difference in the load input to both frames and increases the energy absorption of the non-collision side frame.

METHOD

The basic principle is to generate a counterforce against the lateral loads during transmitting the load from barrier to the frames. To achieve this, a bow-shaped rear bumper beam structure was devised. The rear bumper beam corresponds to the bow and the newly added connection plate to the string. The lateral load increase is suppressed and load distribution to the rear frame is maintained.

RESULTS

The designed rear bumper beam and rear components equipped with the rear bumper beam were both prepared and evaluated by drop test. With testing of the rear bumper beam, it was demonstrated that the load in the lateral direction, which conventionally generates over 80 kN, could be canceled. Tests of the rear component demonstrated that load distribution to the rear frame could be maintained, and the energy absorption of the non-collision side frame could be enhanced by 35 times. The total energy absorption of the barrier and the two frames was demonstrated to increase 2.9 times.

CONCLUSION

The bow-shaped rear bumper beam was designed to distribute the load evenly to the collision and non-collision side frames, and to deform both frames, thereby achieving a higher energy absorption of the entire vehicle body. This is expected to be applicable to electric vehicles and FCVs, which require more energy absorption with increased vehicle weight.

Comparing Statistics and Machine Learning to Detect Insincere Grip Force Testing Using Manugraphy

Background Currently, there are no tests that have been proven to be capable of rating an individual's grip force measurement as sincere or insincere. However, different parameters have been found to vary in grip force testing for maximal versus submaximal effort. A novel data analysis and processing approach might be key to improving these measurements. This study explores the use of a machine learning (ML) algorithm as a means to more accurately determine the sincerity or insincerity of grip force testing. The ML algorithm compares the hand's load distribution pattern with the information generated using conventional statistical methods. Methodology This study uses manugraphy data collected as part of a previous investigation that analyzed load distribution patterns of the right and left hands of 54 healthy subjects. The subjects underwent grip force testing using maximal or submaximal effort, and the percentage contributions of each of the seven defined anatomical areas of the hand were calculated with respect to the total load applied. The predictions based on the load distribution and its use for rating individual grip force measurements as sincere or insincere were compared with the results of conventional statistical methods (thresholds for a bi-manual area-to-area comparison) and an ML algorithm. Results Based on an area-to-area comparison, our method achieved a sensitivity of 54% and a specificity of 78% to detect insincere effort. A predictive ML model developed using these data was capable of recognizing submaximal effort based on the hand's load distribution pattern, determining a sensitivity of 94% and a specificity of 99%. Conclusions Compared to conventional methods, the use of an ML algorithm considerably improved the validity of manugraphy results in discerning the sincerity or insincerity of grip effort.

Entropic Balance Conditions and Optimization of Distillation Column System

The paper considers the limitation problem of the distillation column systems separating multicomponent mixtures with serial and parallel structures. The solution takes into account the irreversibility of processes. Using entropic balance conditions, the dependence of load on heat consumption is obtained for a binary distillation column. This dependence is parameterized through two characteristic coefficients–reversible efficiency and irreversibility factor. This dependence was used to solve problems of distribution of heat and raw material fluxes in parallel column structure and selection of optimal separation order in serial structure. The obtained results make it possible to estimate the minimum heat consumption for the separation of a given flow of raw materials, the maximum productivity, and efficiency of the system.

Functional foot trimming to balance load distribution between the paired forelimb claws in dairy cows: An experimental study

In standing dairy cows, the medial claws carry most of the load of the forelimb. The goal of our experimental study was to investigate how even load distribution can be achieved between the paired forelimb claws through foot trimming. We measured vertical ground reaction forces, mean and maximum pressures, and contact areas under the sound forelimb claws of 28 nonlame dairy cows using a force plate and a pressure plate. The experimental setup consisted of 3 measurement situations: (1) baseline measurements made after routine foot trimming, (2) measurements made with plywood plates, 3 mm in thickness, attached to both lateral claws, and (3) measurements made with the same plywood plates attached to both medial claws. After routine foot trimming, the medial claws carried 70.1% of the entire forelimb load with its palmar zone bearing 54.0% of the entire forelimb load. Even load distribution between the paired claws was achieved when the plywood plates were attached to the lateral claws, whereas plates on the medial claws increased the load discrepancy. The pressures on the medial claws were reduced by attaching the plywood plates to the lateral claws but remained uneven between paired claws and claw zones. The palmar zone of the medial claws was the region subjected to the greatest force and highest pressures in all situations. A drawback of the study was that the plywood plates increased the contact area and therefore reduced the mean and maximum pressures in the claws they were attached to. We concluded that equal load distribution between the forelimb claws was achieved in our setting when the lateral claws were left 3 mm higher than the medial claws.

Evaluation of Load Distributions and Contact Areas in 4 Common Grip Types Used in Daily Living Activities

PURPOSE

Grip analysis systems, with sensors quantifying load distributions and contact areas applied by the hand while grasping objects, are useful for collecting and recording instant data; these systems are popular in hand assessment. The purpose of this study was to determine the load distribution (LD) and contact area (CA) size of the palmar surface of the hand during 4 common grip types used in activities of daily living (standard, lateral, pinch, and tripod grips).

METHODS

A convenience sample of 80 right-handed subjects were enrolled in this study. Participants wore special gloves equipped with sensors and grasped a variety of objects. Contact area size and LD were determined for the 4 grip types.

RESULTS

The CA and the LD were different for each grip. For standard grip, although the largest CA occurred at the metacarpophalangeal joint level, the largest LD was over the middle finger pulp. For standard grip, index, middle, and ring fingers appear to be loaded with almost the same frequency as the thumb. Although CA on the thumb was maximum in the pinch, lateral and tripod grip types, the LD on the thumb was not.

CONCLUSIONS

This study shows that the LD and CA patterns differ widely among standard, pinch, lateral, and tripod grips. The percentage of CA occurring on the thumb was maximum in all grip types.

CLINICAL RELEVANCE

This information is important to optimize the design of artificial manipulators or assistive devices and to optimize the hand rehabilitation process. In addition, results of the study can be used to guide the design of prostheses and biomedical implants better.

Effects of Exoskeleton Gait Training on Balance, Load Distribution, and Functional Status in Stroke: A Randomized Controlled Trial

Background: As a result of stroke, patients have problems with locomotion and transfers, which lead to frequent falls. Recovery after stroke is a major goal of rehabilitation, but it is difficult to choose which treatment method is most beneficial for stroke survivors. Recently, powered robotic exoskeletons are used in treatment to maximize the neural recovery of patients after stroke, but there are no studies evaluating the changes in balance among patients rehabilitated with an exoskeleton. Purpose: The aim of this study was to evaluate the effects of Ekso GT exoskeleton-assisted gait training on balance, load distribution, and functional status of patients after ischemic stroke. Methods: The outcomes are based on 44 patients aged 55-85 years after ischemic stroke who were previously randomly assigned into two groups: experimental (with Ekso GT rehabilitation) and control (with classical rehabilitation). At baseline and after 4 weeks of treatment, the patients were evaluated on balance, load distribution, and functional status using, respectively a stabilometric platform, the Barthel Index, and the Rivermead Mobility Index. Results: In the experimental group, balance improved regarding the variables describing sway area as ellipse major and minor axes. In the control group, improvement was noted in sway velocity. After the therapy, total load distribution on feet in both groups showed a small and insignificant tendency toward reduction in the amount of uninvolved limb loading. In the control group, significant load transfer from the backfoot to the forefoot was noted. Both forms of rehabilitation caused significant changes in functional status. Conclusions: Both training with the use of the Ekso GT exoskeleton and classical physiotherapy lead to functional improvement of patients after ischemic stroke. However, in the experimental group, improvement was observed in a larger number of categories, which may suggest potentially greater impact of treatment with the exoskeleton on functional status. Also, both forms of rehabilitation caused significant changes in balance, but we have noted some trends indicating that treatment with exoskeleton may be more beneficial for some patients. The load transfer from the backfoot to the forefoot observed in the control group was an unfavorable phenomenon. We suggest that the Ekso GT exoskeleton may be a promising tool in the rehabilitation of patients after stroke. Trial registration: Trial ID ACTRN12616000148471.

Contralateral seventh cervical nerve transfer can affect the pennation angle of the lower limb in spastic hemiplegia patients: An observational case series study

INTRODUCTION

We previously reported transferring seventh cervical (C7) nerve from unaffected side to affected side in patients with spastic hemiplegia due to chronic cerebral injury, to improve function and reduce spasticity of paralyzed upper limb. In the clinics, some patients also reported changes of spasticity in their lower limb, which could not be detected by routine physical examinations. Pennation angle of muscle can indirectly reflect the condition of spasticity. The purpose of this study was to evaluate whether this upper limb procedure may affect spasticity of lower limb, using ultrasonography to detect changes of muscle pennation angle (PA).

METHODS

Twelve spastic hemiplegia patients due to cerebral injury including stroke, cerebral palsy, and traumatic brain injury, who underwent C7 nerve transfer procedure, participated in this study. B-mode ultrasonography was used to measure PA of the gastrocnemius medialis (GM) muscle at rest preoperatively and postoperatively. The plantar load distribution of the lower limbs was evaluated using a Zebris FDM platform preoperatively and postoperatively.

RESULTS

The PA of the GM was significantly smaller on the affected side than that of unaffected side before surgery. On the affected side, the postoperative PA was significantly larger than preoperative PA. On the unaffected side, the postoperative PA was not significantly different compared to preoperative PA. The postoperative plantar load distribution of the affected forefoot was significantly smaller than preoperative load distribution, which was consistent with ultrasonography results.

CONCLUSIONS

This study indicates that C7 nerve transfer surgery for improving upper limb function can also affect muscle properties of lower limb in spastic hemiplegia patients, which reveals a link between the upper and lower limbs. The interlimb interactions should be considered in rehabilitation physiotherapy, and the regular pattern and mechanism need to be further studied.

Influence of Maximal or Submaximal Effort on the Load Distribution of the Hand Analyzed by Manugraphy

PURPOSE

This study aims to investigate if the hands' load-distribution pattern differs during maximal and submaximal grip.

METHODS

Fifty-four healthy subjects used the 200-mm Manugraphy cylinder to assess the load-distribution pattern of both hands. On 2 testing days, the subjects performed grip-force testing: 1 hand with maximal effort and the other with submaximal effort. Sides changed for the second testing day. The whole contact area of the hand was sectioned into 7 anatomical areas, and the percent contribution of each area, in relation to the total load applied, was calculated. Maximal and submaximal efforts were compared across the 7 areas in terms of load contributions.

RESULTS

Comparing maximum effort of the left and right hand, the load distribution was very similar without statistically significant differences between the corresponding areas. Comparing the maximal and the submaximal effort for each hand, 4 (left) and 5 (right) of the 7 corresponding areas showed statistically significant differences. Comparing the right hand, performing with maximal effort, with the left hand, performing with submaximal effort, 5 areas varied significantly. With the right hand performing submaximal effort, all 7 anatomical areas were significantly different.

CONCLUSIONS

The load distribution of a healthy hand is different when performing with submaximal effort compared with maximal effort. To analyze a hand's load-distribution pattern, the opposite hand can be used as a reference.

CLINICAL RELEVANCE

The hand's load-distribution pattern may be a useful indication of submaximal effort during grip-force testing.

The Effect of Midcarpal Versus Total Wrist Fusion on the Hand's Load Distribution During Gripping

PURPOSE

To analyze the total grip force and load distribution of the hand with midcarpal fusion (MCF) and total wrist fusion (TWF).

METHODS

Twelve patients with unilateral TWF and 12 patients with unilateral MCF were assessed at an average 64 months (range, 19-100 months) postoperatively. The total grip force and load distribution of both hands were measured by the Manugraphy system using 3 cylinder sizes. The load applied to 7 anatomical areas of the hand during cylinder grip was analyzed, comparing the operated and the nonsurgical hands.

RESULTS

For the 100 mm and 150 mm cylinders, a significantly lower total grip force was found in hands operated with either TWF or MCF. For the 200 mm cylinder, there was a significant difference between nonsurgical hands and those with MCF but not between nonsurgical hands and those with TWF. For the 100 mm cylinder, the difference between nonsurgical and operated hands was greater in hands with TWF than those with MCF. For the load distribution of the hand, no differences between the operated and the nonsurgical hand were found for either MCF or TWF.

CONCLUSIONS

MFC and TWF resulted in a reduced cylinder grip force. With respect to the load distribution, neither procedure influenced the relative contribution that each area of the hand produced during cylinder grip.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic III.

Multipath routing in wireless sensor networks: survey and research challenges

A wireless sensor network is a large collection of sensor nodes with limited power supply and constrained computational capability. Due to the restricted communication range and high density of sensor nodes, packet forwarding in sensor networks is usually performed through multi-hop data transmission. Therefore, routing in wireless sensor networks has been considered an important field of research over the past decade. Nowadays, multipath routing approach is widely used in wireless sensor networks to improve network performance through efficient utilization of available network resources. Accordingly, the main aim of this survey is to present the concept of the multipath routing approach and its fundamental challenges, as well as the basic motivations for utilizing this technique in wireless sensor networks. In addition, we present a comprehensive taxonomy on the existing multipath routing protocols, which are especially designed for wireless sensor networks. We highlight the primary motivation behind the development of each protocol category and explain the operation of different protocols in detail, with emphasis on their advantages and disadvantages. Furthermore, this paper compares and summarizes the state-of-the-art multipath routing techniques from the network application point of view. Finally, we identify open issues for further research in the development of multipath routing protocols for wireless sensor networks.