Loading Arm Research Articles

Study of the Loading Arms of the Side-Crane Used for Container

As the important device, self-loading device plays a key role in the side-crane used for container. And as the key component of the self-loading device, loading arm’s strength analysis is very important. FEA is introduced into the arm’s strength and rigidity analysis, and under the precondition of satisfying allowable stress, minimum weight of the arm is taken as the design target. Ulteriorly, by obtaining optimal geometric parameters, the loading arm’s optimization design can be realized and its manufacture cost can be reduced.

Increased Plasma CXCL10 May be a Marker of Increased Risk of Immune Restoration Disease Associated With Nonviral Pathogens

Increased Plasma CXCL10 May be a Marker of Increased Risk of Immune Restoration Disease Associated With Nonviral Pathogens

Theoretical Analysis and Experimental Research on Emergency Release Devices of Loading Arm

This paper introduces the components and structure characteristics of Loading arms Emergency Release Device(ERD). It establishes mathematic model and carried on theory analysis and test analysis of the ERD. The theory analysis is identical with test results so that it can provide the theory basis for optimum design.

Enhanced mechanical transparency during practice impedes open-loop control of a complex tool

We investigated the impact of enhanced mechanical transparency during practice on closed-loop performance as well as on the acquisition of an internal representation of the visuo-motor transformation of a lever. Three groups of participants controlled a cursor on a monitor by moving the effort arm of a sliding two-sided lever. The level of mechanical transparency was manipulated by varying the amount of conceptual knowledge about the tool the participants were using as well as by the visualization of the effective part of the tool on the monitor. While for groups cursor- and cursor+ only a cursor representing the tip of the load arm of the lever was visible, group shaft was additionally provided with a representation of the load arm on the monitor. The cursor groups differed in conceptual knowledge about the tool, with only group cursor+ being informed that they were controlling a two-sided lever. Enhanced mechanical transparency, resulting from the visibility of the lever arm, boosted performance in terms of faster and straighter movements when concurrent visual feedback was available, and therefore closed-loop control was possible. In contrast, a detrimental effect of enhanced mechanical transparency during practice on the accuracy of the internal representation of the visuo-motor transformation was observed. When assessing open-loop control in test trials without visual feedback, participants who had previously practiced the tool transformation with the visible lever arm showed larger end point errors than those who had practiced with the cursor only. These findings support the notion that enhanced mechanical transparency of a tool is a type of environmental support which boosts closed-loop performance, but impedes open-loop performance, most likely by serving as a substitute for an internal representation. When practice conditions facilitate closed-loop control, the acquisition of an accurate internal representation of a novel visuo-motor transformation seems to be hampered.

Calcaneal proportions in primates and locomotor inferences in Anchomomys and other Palaeogene Euprimates

Foot proportions, and in particular the lengthening of the tarsal elements, play a fundamental role in the discussion on the locomotor adaptations of Palaeogene primates. The elongation of the distal portion of the tarsus, particularly the anterior part of the calcaneus, is frequently interpreted as an adaptation to leaping and has played a fundamental role in the reconstruction of the locomotor adaptations of the earliest primates. Here, we report an allometric analysis of calcaneal proportions in primates and other mammals, in order to determine the actual differences in calcaneal proportions. This analysis reveals that primates as a group display a relatively longer distal calcaneus, relative to both total calcaneal length and body mass, when compared with other mammals. Contrary to current expectations, morphofunctional analysis indicates that a moderate degree of calcaneal elongation is not an adaptation to leaping, but it is merely a compensatory mechanism to recover the lost load arm (metatarsal length) when the foot adopts a grasping function, in order to maintain the same locomotor efficiency. Leaping can be inferred only when anterior calcaneal length departs from the scaling of non-specialized primate groups. The role of leaping on the inferred locomotor repertoire of earliest primates needs to be revised considering the results of this work.

Utility of routine viral load, CD4 cell count, and clinical monitoring among adults with HIV receiving antiretroviral therapy in Uganda: randomised trial

Objective To evaluate the use of routine laboratory monitoring in terms of clinical outcomes among patients receiving antiretroviral therapy (ART) in Uganda.Design Randomised clinical trialSetting A home based ART programme...

Study of the Modeling of the Gear Dynamics Considering Mesh Stiffness and Sliding Friction

Time- varying mesh stiffness and sliding friction between teeth are the great excitation for vibration and noise in gears system. But, there are rarely studies on this topic. This paper proposes a new dynamic modeling of gear system, which is effect of mesh stiffness variation, sliding friction and distribution of load. Firstly, the expression of time-varying mesh stiffness is gained, which is a period function. Secondly, a new friction modeling has the same period as mesh stiffness, is proposed. Thirdly, friction torque of each gear pair is calculated respectively, which is considering the distribution of load and time-varying friction arm. Finally, because all parameter have the same cycle, it is easy to get the approximate analytical solution to non-line model of gear dynamic by fourier transform.

Measurements of the Static Friction Coefficient Between Bone and Muscle Tissues

This study aimed at measuring the static coefficient of friction (mu) between bone and skeletal muscle tissues in order to support finite element (FE) modeling in orthopaedic and rehabilitation research, where such contact conditions need to be defined. A custom-made friction meter (FM) that employs the load cell and motion-controlled loading arm of a materials testing machine was designed for this study. The FM was used to measure mu between fresh ulna bones and extensor muscles surrounding the ulna, which were harvested from five young adult pigs. Mean bone-muscle mu were between 0.36 and 0.29, decreased with the increase in loads applied on the bone (p<0.05) and plateaued at a mean approximately 0.3 for loads exceeding 4 N. Hence, for FE modeling of bone-muscle contacts through which loads with magnitudes of kgs to 10s-of-kgs are transferred, assuming mu of approximately 0.3 appears to be appropriate.

Dentin removal efficacy over time of the Buc-1 ultrasonic tip

The purpose of this study was to determine the loss of efficacy over time of the Buc-1 ultrasonic tip in dentin blocks. An ultrasonic handpiece was mounted to the loading arm of a universal testing machine and a downward force of 15 g was applied in 20-sec cycles for a total of 30 min of instrumentation. Efficacy was measured by the change in weight of the dentin block to the nearest 0.01 mg after 2, 10, 20, and 30 minutes of instrumentation (n = 5 tips). Dentin removal decreased significantly between 2 and 10 minutes of instrumentation with no further significant decrease after 20 or 30 minutes (1-factor analysis of variance: alpha = .05). The evidence suggests there is a significant decrease in dentin removal efficacy of the Buc-1 tip after 10 minutes of instrumentation. Continued instrumentation for up to 30 minutes showed no further decrease in efficacy.

Ontogeny of joint mechanics in squirrel monkeys (Saimiri boliviensis): functional implications for mammalian limb growth and locomotor development

Juvenile animals must often compete against adults for common resources, keep pace during group travel and evade common predators, despite reduced body size and an immature musculoskeletal system. Previous morphometric studies of a diverse array of mammals, including jack rabbits, cats and capuchin monkeys, have identified growth-related changes in anatomy, such as negative allometry of limb muscle mechanical advantage, which should theoretically permit young mammals to overcome such ontogenetic limits on performance. However, it is important to evaluate the potential impact of such ;compensatory' growth trajectories within the context of developmental changes in locomotor behavior. I used standard kinematic and kinetic techniques to investigate the ontogenetic scaling of joint postures, substrate reaction forces, joint load arm lengths and external joint moments in an ontogenetic sample of squirrel monkeys (Saimiri boliviensis). Results indicated that young squirrel monkeys were frequently able to limit forelimb and hind limb joint loading via a combination of changes in limb posture and limb force distribution, potentially compensating for limited muscularity at younger ages. These results complement previous morphometric studies and suggest that immature mammals may utilize a combination of behavioral and anatomical mechanisms to mitigate ontogenetic limits on locomotor performance. However, ontogenetic changes in joint posture, not limb length per se, explained most of the variation in load arm lengths and joint loading in growing squirrel monkeys, indicating the importance of incorporating both anatomical and performance measures when studying the ontogeny of limb joint mechanics.

Relative Comparison Method of Rolling Contact Fatigue Performance of Silicon Nitrides by Stepwise Loading Balls-on-Flat Test—A Candidate for Standard Practice for Comparison of RCF Performance

Abstract We have demonstrated a simple comparison method for rolling contact fatigue (RCF) performance of silicon nitrides using the balls-on-flat RCF test under stepwise loading. The RCF performance was evaluated by the mean effective mechanical input (Min)m which is the product of the mean effective load Pm, calculated from test loads and revolutions during the dwell time for each load, and the number of load cycles. The test materials were six kinds of commercially available silicon nitride, four of bearing-grade silicon nitrides (BG) and two general purpose ones (GP). The minimum test loads were 1 and 0.5 kN for BG and GP, respectively. The load was increased stepwise with each step 107 contact cycles unless failure of the specimen was detected by the acceleration pickup mounted on the loading arm of the testing machine. The balls and test specimen were immersed in mineral oil with kinematic viscosities of 8 mm2/s for BG and 68 mm2/s for GP. A clear distinction in (Min)m was made among the BG, and the GP have lower (Min)m compared to BG, despite small differences in conventional mechanical properties such as Vickers hardness, fracture toughness, and elastic modulus. The results of the balls-on-flat RCF test under constant load for one BG lend support to the hypothesis that the loading history in stepwise loading can be converted to the mean effective load Pm. It is also supported by the fact that classification of failure mechanisms in stepwise loading is similar to that for a constant load of 4 kN, which is close to the mean of Pm of the material. These results imply the viability of a standardized comparison method for RCF performance of bearing-grade silicon nitrides as well as screening for poor performance materials.

Ultrawideband Performance of Dielectric Loaded T-Shaped Monopole Transmit and Receive Antenna/EMI Sensor

This letter presents the performance of a T-shaped monopole antenna loaded with an annular dielectric resonator as an ultrawideband transmitting/receiving antenna. By adjusting the length of the monopole and load arm, a 10-dB bandwidth of 110% is achieved while maintaining monopole-like radiation pattern. The antenna factor of the same antenna, while used as electromagnetic interference (EMI) sensor is also presented for the desired and cross-polarized component of incident electric field. The results for antenna factor show an ultrawide bandwidth with the cross-polarization isolation better than 86 dB/m for the T-monopole/DRA as EMI sensor. The simulated result for return loss is verified with the measured data from a prototype antenna.

SIMULTANEOUS TRAJECTORY MANIPULATION OF A DUAL-ARM ROBOT USING SLIDING MODE CONTROL

Dual-arm robotic system for load transportation in hazardous environments is considered in this study. First, physical model of the robot arms with the load is presented and related equations of motion are obtained. Friction forces arising on the contact points between the load and robot arm tips are also taken into account. Then, robust non-chattering sliding mode control is used in order to obtain the joint torques, which makes the robot track the trajectory and move the load to its new location. Finally, numerical results are presented. These results verify that this type of robot systems with proposed sliding mode control method can be used in hazardous applications safely.

Cross-sectional Bone Distribution in the Mandibles of Gouging and Non-gouging Platyrrhini

Recent morphometric analyses have led to dissimilar conclusions about whether the jaws of tree-gouging primates are designed to resist the purportedly large forces generated during this biting behavior. We further address this question by comparing the cross-sectional geometry of the mandibular corpus and symphysis in tree-gouging common marmosets (Callithrix jacchus) to nongouging saddleback tamarins (Saguinus fuscicollis) and squirrel monkeys (Saimiri sciureus). As might be expected, based on size, squirrel monkeys tend to have absolutely larger cross-sectional areas at each tooth location sampled, while saddleback tamarins are intermediate, followed by the smaller common marmosets. Similarly, the amount and distribution of cortical bone in squirrel monkey jaws provides them with increased ability to resist sagittal bending (I xx ) and torsion (K) in the corpus as well as coronal bending (I xx ) and shearing in the symphysis. However, when the biomechanical parameters are scaled to respective load arm estimates, there are few significant differences in relative resistance abilities among the 3 species. A power analysis indicates that we cannot statistically rule out subtle changes in marmoset jaw form linked to resisting loads during gouging. Nevertheless, our results correspond to studies in vivo of jaw loading, field data, and other comparative analyses suggesting that common marmosets do not generate relatively large bite forces during tree gouging. The 3 species are like most other anthropoids in having thinner bone on the lingual than on the buccal side of the mandibular corpus at M1. The similarity in corporal shape across anthropoids supports a hypothesized stereotypical pattern of jaw loading during chewing and may indicate a conserved pattern of mandibular growth for the suborder. Despite the overall similarity, platyrrhines may differ slightly from catarrhines in the details of their cortical bone distribution.

Ankle Ligament Tensile Forces at the End Points of Passive Circumferential Rotating Motion of the Ankle and Subtalar Joint Complex

Ankle ligament injuries and instability are commonly observed. Knowledge of the relationship between the foot position and tensile forces of the ankle ligaments could be useful for treatment of ankle ligament disorders. The aim of this study was to measure the tensile forces of the ankle ligaments at the end points of passive circumferential rotating motion of the ankle and subtalar joint complex in various foot positions. Ligament tensile forces of the anterior talofibular (ATF), calcaneofibular (CF), posterior talofibular (PTF), and tibiocalcaneal (TC) ligaments were measured simultaneously in eight cadaver specimens, with a force probe in each ligament in a custom-made ankle ligament testing device. Weights of 0.5 kg and 1 kg were applied to the foot through a loading arm to provide axial compression and a bending moment to the foot and ankle. The position of the loading arm was changed circumferentially in 10-degree increments. Maximal tensile force in the ATF ligament was observed in supination with plantarflexion (108 +/- 62.8 N at 0.5 kg and 130 +/- 39.1 N at 1 kg). The maximal tensile force in the CF ligament was observed in pronation with plantarflexion (68 +/- 48.6 N at 0.5 kg and 135 +/- 92.9 N at 1 kg). The maximal tensile force in the PTF ligament was observed in dorsiflexion (131 +/- 80.1 N at 0.5 kg and 109 +/- 36.3 N at 1 kg). The maximal tensile force of the TC ligament was observed in pronation with plantarflexion (49.0 +/- 80.1 N at 0.5 kg and 67.4 +/- 69.6 N at 1 kg). Relatively high magnitudes of tensile force were observed in the ankle ligaments, and the peak forces were related to the anatomic position of individual ligaments. The ATF ligament has an important role in the supination position in plantarflexion, CF and TC ligaments also are important for pronation in plantarflexion, and the PTF is an important stabilizer in dorsiflexion. This study provides baseline information for further research related to ligament instability and reconstruction operations.

A quantitative risk analysis approach to port hydrocarbon logistics

A method is presented that allows quantitative risk analysis to be performed on marine hydrocarbon terminals sited in ports. A significant gap was identified in the technical literature on QRA for the handling of hazardous materials in harbours published prior to this work. The analysis is extended to tanker navigation through port waters and loading and unloading facilities. The steps of the method are discussed, beginning with data collecting. As to accident scenario identification, an approach is proposed that takes into account minor and massive spills due to loading arm failures and tank rupture. Frequency estimation is thoroughly reviewed and a shortcut approach is proposed for frequency calculation. This allows for the two-fold possibility of a tanker colliding/grounding at/near the berth or while navigating to/from the berth. A number of probability data defining the possibility of a cargo spill after an external impact on a tanker are discussed. As to consequence and vulnerability estimates, a scheme is proposed for the use of ratios between the numbers of fatal victims, injured and evacuated people. Finally, an example application is given, based on a pilot study conducted in the Port of Barcelona, where the method was tested.

Randomized phase III study comparing standard TIW and weekly dosage of epoetin alfa with 2 weeks loading dose: Preliminary results

8215 Background: Epoetin alfa efficacy in anemic cancer patients has already been proved by both open-label and placebo-controlled clinical trials. The standard treatment, 10.000 IU TIW in Europe and 40.000 QW in USA, yields a reproducible response of 1 g/dl Hb in 4 weeks and about 2 g/dl Hb in 8 weeks, being the mean baseline Hb near 10.0 g/dl. No data is available on the comparison of the two randomized schedules. Aim: The present study compares 10.000 IU TIW treatment with a loading dose of 40.000 IU twice a week administered for the first two weeks followed by 40.000 IU QW to the end of chemotherapy schedule. The main endpoint is the response to the different schedules of epoetin alfa measured after 2 weeks. Severely anemic cancer patients (baseline Hb≤9.5 g/dl) represent the study population of the present trial. Results: The study recruited 202 patients, main diagnoses being breast, lung and colorectal cancer. Data on the first 64 patients is available so far. Baseline Hb level was similar for both groups being 8.9 g/dl for 10.000 IU and 9.1 g/dl for 40.000 IU group. After 2-weeks treatment Hb level was respectively 9.4 g/dl and 9.9 g/dl with an increase of 0.48 g/dl in the 10000 IU arm and 0.82 g/dl in the loading arm. A statistically significant difference has been observed as early as week two (p<0.001; Repeated Measures ANOVA, W-B Design and Tukey-Kramer Multiple Comparison test). Data on long-term comparison between groups will be available for ASCO meeting. Conclusion: After two-weeks treatment, 4 doses of epoetin alfa 40.000 IU allow a quicker and sustained response with respect to standard dosage. Data on the comparison between 10.000 IU TIW and 40.000 IU QW in terms of haematological response and QoL will be presented. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Ortho-Biotech Ortho-Biotech

Micro-scale abrasive wear of silicon nitride, sialon–TiB 2 composites and D2 tool steel using a multiple load method

The addition of TiB 2 to sialon has previously been shown to lead to improvements in tribological performance when using pin-on-disc testing. In this study the specific wear rates of Si 3N 4, sialon–TiB 2 composites and D2 tool steel have been measured using micro-scale abrasive testing. Two variations of the micro-scale abrasive wear test have been used, free ball and fixed ball, and the results are compared. A method has been developed for the accurate measurement of the specific wear rate using multiple loads on the fixed ball apparatus. The multiple load method eliminates the dependence of the result on the accuracy of the balancing of the load arm. Scanning electron microscopy has been used to study the active wear mechanisms and the effect of increasing the applied load. The “severity of contact” model has been evaluated as a method for predicting the transition from three body rolling wear to two body grooving wear with varying load. Increasing the applied load led to slurry starvation and ridge formation before the predicted two body grooving wear could occur.

Analysis of the human and ape foot during bipedal standing with implications for the evolution of the foot

The ratio of the power arm (the distance from the heel to the talocrural joint) to the load arm (that from the talocrural joint to the distal head of the metatarsals), or RPL, differs markedly between the human and ape foot. The arches are relatively higher in the human foot in comparison with those in apes. This study evaluates the effect of these two differences on biomechanical effectiveness during bipedal standing, estimating the forces acting across the talocrural and tarsometatarsal joints, and attempts to identify which type of foot is optimal for bipedal standing. A simple model of the foot musculoskeletal system was built to represent the geometric and force relationships in the foot during bipedal standing, and measurements for a variety of human and ape feet applied. The results show that: (1) an RPL of around 40% (as is the case in the human foot) minimizes required muscle force at the talocrural joint; (2) the presence of an high arch in the human foot reduces forces in the plantar musculature and aponeurosis; and (3) the human foot has a lower total of force in joints and muscles than do the ape feet. These results indicate that the proportions of the human foot, and the height of the medial arch are indeed better optimized for bipedal standing than those of apes, further suggesting that their current state is to some extent the product of positive selection for enhanced bipedal standing during the evolution of the foot.

Sexual Dimorphism of the Calcaneus of South African Blacks

Forensic anthropology is a rapidly growing field in South Africa and skeletal biologists are often called upon by the police to assist in personal identification from skeletal remains, which are recovered in suspected cases of homicide and suicide and in mass disaster. Measurements of the calcaneus have been shown to be sexually dimorphic in South African whites. Since the validity of discriminant function equations in sex determination is population specific, the aim of the present study was to derive similar equations for the calcanei of the South African blacks. The bones that were used in this study were obtained from the Raymond A. Dart Collection of Human Skeletons, School of Anatomical Sciences, University of the Witwatersrand, Johannesburg. One hundred and sixteen (116) intact and non-pathological calcanei, consisting of 58 males and 58 females and belonging to individuals whose age at death ranged between 22 and 75 years, were selected by the simple random sampling technique. The measured variables included the maximum length, the load arm length, the dorsal articular facet length, the body height, the maximum height, the cuboidal facet height, the middle breadth, the dorsal articular facet breadth and the maximum breadth. Discriminant function analyses were done using the Statistical Product and Service Solutions (SPSS) program. All measured parameters of the calcaneus showed significant sexual differences. Length measurements were found to be the most sexually dimorphic. Combinations of variables provided better estimate of sex (79%-86%) than individual variables (64%-79%).