Contact Duration Time Research Articles

Low velocity impact response of functionally graded carbon nanotube reinforced composite beams in thermal environment

Response of functionally graded carbon nanotube reinforced composite (FG-CNTRC) beam subjected to the action of an impacting mass is analyzed. Timoshenko beam theory is used to estimate the kinematics of the beam. Material properties of the fibers and polymeric matrix are assumed to be temperature dependent. Both uniform and functionally graded distribution of CNTs are taken into account. Material properties of the composite are obtained using a refined rule of mixture. Contact force between the impactor and the beam is obtained with the aid of the conventional Hertz law. The governing dynamic equations of the system, are obtained using the conventional polynomial Ritz method applied to the total energy of the system. The solution of the resulting equations is traced in time using the well-known Runge–Kutta method. After examining the validity of the present solution, parametric studies are conducted to examine the influences of thermal environment, volume fraction of the CNTs, distribution of CNTs, initial velocity of the impactor and the impactor mass. Numerical results reveal that as the volume fraction of CNTs increases in the beam, peak contact force increases and the contact time decreases. Furthermore, temperature rise results in higher contact time duration and lower peak contact force.

Neuro-mechanical and metabolic adjustments to the repeated anaerobic sprint test in professional football players.

This study aimed to determine the neuro-mechanical and metabolic adjustments in the lower limbs induced by the running anaerobic sprint test (the so-called RAST). Eight professional football players performed 6 × 35 m sprints interspersed with 10 s of active recovery on artificial turf with their football shoes. Sprinting mechanics (plantar pressure insoles), root mean square activity of the vastus lateralis (VL), rectus femoris (RF), and biceps femoris (BF) muscles (surface electromyography, EMG) and VL muscle oxygenation (near-infrared spectroscopy) were monitored continuously. Sprint time, contact time and total stride duration increased from the first to the last repetition (+17.4, +20.0 and +16.6 %; all P < 0.05), while flight time and stride length remained constant. Stride frequency (-13.9 %; P < 0.001) and vertical stiffness decreased (-27.2 %; P < 0.001) across trials. Root mean square EMG activities of RF and BF (-18.7 and -18.1 %; P < 0.01 and 0.001, respectively), but not VL (-1.2 %; P > 0.05), decreased over sprint repetitions and were correlated with the increase in running time (r = -0.82 and -0.90; both P < 0.05). Together with a better maintenance of RF and BF muscles activation levels over sprint repetitions, players with a better repeated-sprint performance (lower cumulated times) also displayed faster muscle de- (during sprints) and re-oxygenation (during recovery) rates (r = -0.74 and -0.84; P < 0.05 and 0.01, respectively). The repeated anaerobic sprint test leads to substantial alterations in stride mechanics and leg-spring behaviour. Our results also strengthen the link between repeated-sprint ability and the change in neuromuscular activation as well as in muscle de- and re-oxygenation rates.

A novel contact prediction‐based routing scheme for DTNs

AbstractDelay/disruption tolerant networks (DTNs) make opportunistic communications by utilising the mobility of nodes. The characteristics of high mobility of nodes and high dynamicity of network topology result in an absence of instantaneous end‐to‐end path from any source to a destination and thus make routing a challenge in DTNs. To deal with this issue, researchers have investigated a variety of routing schemes for DTNs based on the prediction of future contacts, in which node mobility is explored and used. However, the previous works did not consider the instant contact information such as the last contact duration time and the instant separation time since the last contact whilst making routing decisions, leading to less prediction accuracy of future contacts and thus worse routing performance. In this paper, a novel contact prediction‐based routing scheme is proposed for DTNs to increase delivery ratio by considering the instant contact information. Specifically, to predict the contact probability of two nodes accurately, the statistical contact information, the instant contact information and the contact transitivity are comprehensively considered. The simulation evaluations show that the proposed contact prediction‐based routing substantially improves delivery ratio and reduces delivery latency and delivery overhead compared with traditional DTN routing schemes. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Evaluation of Dynamic Deformation Properties of Metallic Materials with Different Crystal Structures Using Taylor Impact Test

Investigations on dynamic deformation behavior of metallic materials under high strain rate have been conducted. In this study, the deformation behaviors of metallic materials with different crystal structures were examined through Taylor impact test. As representative materials, HSA800 (body-centered cubic: BCC), OFHC (face-centered cubic: FCC) and Ti-6Al-4V (hexagonal close-packed : HCP) were adopted. Taylor impact tests were carried out in the impact velocity range of 100~270 m/s for BCC and FCC materials and 150~330 m/s for Ti-alloy one. In addition, an 8-Ch high-speed photography system was used to provide a series of images representing the plastic deformation behavior of a projectile during Taylor test. The dynamic yield strength and the strain rate were calculated based on the contact time duration of projectile determined from high-speed images. From the result, the strain rate dependency of the dynamic yield strength varied depending on the material adopted. Bulging occurred at the impact part was more significant in FCC material than in BCC one, while a shear band occurred in the Ti-alloy specimen when the impact velocity of projectile exceeded 270 m/s.

Optimizing the Passenger Air Bag of an Adaptive Restraint System for Multiple Size Occupants

Objective: The development of the adaptive occupant restraint system (AORS) has led to an innovative way to optimize such systems for multiple size occupants. An AORS consists of multiple units such as adaptive air bags, seat belts, etc. During a collision, as a supplemental protective device, air bags can provide constraint force and play a role in dissipating the crash energy of the occupants’ head and thorax. This article presents an investigation into an adaptive passenger air bag (PAB).Methods: The purpose of this study is to develop a base shape of a PAB for different size occupants using an optimization method. Four typical base shapes of a PAB were designed based on geometric data on the passenger side. Then 4 PAB finite element (FE) models and a validated sled with different size dummy models were developed in MADYMO (TNO, Rijswijk, The Netherlands) to conduct the optimization to obtain the best baseline PAB that would be used in the AORS. The objective functions—that is, the minimum total probability of injuries (∑Pcomb) of the 5th percentile female and 50th and 95th percentile male dummies—were adopted to evaluate the optimal configurations. The injury probability (Pcomb) for each dummy was adopted from the U.S. New Car Assessment Program (US-NCAP).Results: The parameters of the AORS were first optimized for different types of PAB base shapes in a frontal impact. Then, contact time duration and force between the PAB and dummy head/chest were optimized by adjusting the parameters of the PAB, such as the number and position of tethers, lower the Pcomb of the 95th percentile male dummy.Conclusions: According to the optimization results, 4 typical PABs could provide effective protection to 5th and 50th percentile dummies. However, due to the heavy and large torsos of the 95th percentile occupants, the current occupant restraint system does not demonstrate satisfactory protective function, particularly for the thorax.

Changes in Running Mechanics and Spring-Mass Behaviour during a 5-km Time Trial

Research into the biomechanical manifestation of fatigue during exhaustive runs is increasingly popular but additional understanding of the adaptation of the spring-mass behaviour during the course of strenuous, self-paced exercises continues to be a challenge in order to develop optimized training and injury prevention programs. This study investigated continuous changes in running mechanics and spring-mass behaviour during a 5-km run. 12 competitive triathletes performed a 5-km running time trial (mean performance: ̴17 min 30 s) on a 200 m indoor track. Vertical and anterior-posterior ground reaction forces were measured every 200 m by a 5-m long force platform system, and used to determine spring-mass model characteristics. After a fast start, running velocity progressively decreased (- 11.6%; P<0.001) in the middle part of the race before an end spurt in the final 400-600 m. Stride length (- 7.4%; P<0.001) and frequency (- 4.1%; P=0.001) decreased over the 25 laps, while contact time (+ 8.9%; P<0.001) and total stride duration (+ 4.1%; P<0.001) progressively lengthened. Peak vertical forces (- 2.0%; P<0.01) and leg compression (- 4.3%; P<0.05), but not centre of mass vertical displacement (+ 3.2%; P>0.05), decreased with time. As a result, vertical stiffness decreased (- 6.0%; P<0.001) during the run, whereas leg stiffness changes were not significant (+ 1.3%; P>0.05). Spring-mass behaviour progressively changes during a 5-km time trial towards deteriorated vertical stiffness, which alters impact and force production characteristics.

Design and Application of Inter-Satellite Link in Weather Observation Constellation

This paper presents the design and application analysis of the inter-satellite link technique in weather observation satellite constellation. A Walker parameter 18/18/4 satellite constellation with circular orbit at 837 km altitude and 60 degree inclination has been considered. The purposes are to take the weather cloud images of the area from 60 to 180 degree in eastern longitude and 0 to 60 degree in northern latitude, and to transfer the images back to Taiwan ground station as soon as possible. The STK [1] simulation software has been used in analyzing the effects of Doppler phenomenon, azimuth angle, elevation angle and distance between each two satellites. It has been proved that through the use of inter-satellite link technique, the contact time duration between the constellation and ground station has been tremendously increased. Therefore, weather cloud images can be transferred back much more frequently. Analysis results presented in this paper could be the reference for onboard antenna auto-tracking design and power management of the satellite.

Hartmann-Hahn 2D-map to optimize the RAMP-CPMAS NMR experiment for pharmaceutical materials

Cross polarization-magic angle spinning (CPMAS) is the most used experiment for solid-state NMR measurements in the pharmaceutical industry, with the well-known variant RAMP-CPMAS its dominant implementation. The experimental work presented in this contribution focuses on the entangled effects of the main parameters of such an experiment. The shape of the RAMP-CP pulse has been considered as well as the contact time duration, and a particular attention also has been devoted to the radio-frequency (RF) field inhomogeneity. (13)C CPMAS NMR spectra have been recorded with a systematic variation of (13)C and (1)H constant radiofrequency field pair values and represented as a Hartmann-Hahn matching two-dimensional map. Such a map yields a rational overview of the intricate optimal conditions necessary to achieve an efficient CP magnetization transfer. The map also highlights the effects of sweeping the RF by the RAMP-CP pulse on the number of Hartmann-Hahn matches crossed and how RF field inhomogeneity helps in increasing the CP efficiency by using a larger fraction of the sample. In the light of the results, strategies for optimal RAMP-CPMAS measurements are suggested, which lead to a much higher efficiency than constant amplitude CP experiment.

Modified cytotoxicity evaluation of elastomeric impression materials while polymerizing with reduced exposure time

Objective. Cytotoxicity evaluation is an important step in biocompatibility assessment of dental impression materials. Previously, cytotoxicity evaluations were carried out on already set (‘set’) impression materials for contact time or extraction time of 24 h or longer in duration. However, clinically, dental impression materials are in contact with oral tissue while they are being set (‘polymerizing’), for no longer than 10 min. Hence, the aim of this study was to investigate the difference in results between ‘polymerizing’ and ‘set’ forms of impression materials as well as the difference in results between longer duration of contact or extraction time (12 or 24 h) and shorter duration of time (15 or 30 min). Materials and methods. Seven dental impression materials of different chemical compositions were tested. Two commonly used in vitro tests were used—test on extraction and test by direct contact. Both ‘polymerizing’ and ‘set’ forms of impression materials were used with different durations of extraction and contact (15 min, 30 min, 12 h and 24 h). Results. There were significant (p < 0.05) differences of cell viability and cell proliferation between the ‘polymerizing’ and ‘set’ impression materials. Also, significant (p < 0.05) differences were noted with variance in duration of time. Conclusion. In light of the results, it is recommended to use a ‘polymerizing’ state of dental impression material for cytotoxicity evaluation, with 15 or 30 min of contact between cell and dental impression materials and an extraction time of 15 or 30 min that is more reflective of clinical situations.

Repeated sprinting on natural grass impairs vertical stiffness but does not alter plantar loading in soccer players

This study aimed to determine changes in spring-mass model (SMM) characteristics, plantar pressures, and muscle activity induced by the repetition of sprints in soccer-specific conditions; i.e., on natural grass with soccer shoes. Thirteen soccer players performed 6×20m sprints interspersed with 20s of passive recovery. Plantar pressure distribution was recorded via an insole pressure recorder device divided into nine areas for analysis. Stride temporal parameters allowed to estimate SMM characteristics. Surface electromyographic activity was monitored for vastus lateralis, rectus femoris, and biceps femoris muscles. Sprint time, contact time, and total stride duration lengthened from the first to the last repetition (+6.7, +12.9, and +9.3%; all P<0.05), while flight time, swing time, and stride length remained constant. Stride frequency decrease across repetitions approached significance (-6.8%; P=0.07). No main effect of the sprint number or any significant interaction between sprint number and foot region was found for maximal force, mean force, peak pressure and mean pressure (all P>0.05). Center of mass vertical displacement increased (P<0.01) with time, together with unchanged (both P>0.05) peak vertical force and leg compression. Vertical stiffness decreased (-15.9%; P<0.05) across trials, whereas leg stiffness changes were not significant (-5.9%; P>0.05). Changes in root mean square activity of the three tested muscles over sprint repetitions were not significant. Although repeated sprinting on natural grass with players wearing soccer boots impairs their leg-spring behavior (vertical stiffness), there is no substantial concomitant alterations in muscle activation levels or plantar pressure patterns.

Repeated sprinting on natural grass impairs vertical stiffness but doesn't alter plantar loading in Qatari soccer players

Background: The ability of players to recover and reproduce sprint performance is a crucial fitness component in soccer. In recent years, there has been an exponential interest in the study of neuro-physiological mechanisms limiting performance during repeated-sprint tests, whereas relatively little attention has been given to the biomechanical manifestation of fatigue. Understanding such factors is critical to performance enhancement and injury prevention strategies in soccer. Aim: This study aimed to determine changes in spring-mass model characteristics, plantar pressures and muscle activity induced by the repetition of sprints in soccer-specific conditions i.e. on natural grass with soccer shoes. Methods: Thirteen soccer players, members of two under nineteen Qatar Youth League teams, performed 6 x 20m sprints interspersed with 20s of passive recovery. Plantar pressure distribution was recorded via an insole pressure recorder device divided into nine areas for analysis. Stride temporal parameters allowed the estimation of spring-mass model characteristics. Surface electromyographic activity was monitored for vastus lateralis, rectus femoris and biceps femoris muscles. Results: Sprint time, contact time and total stride duration lengthened from the first to the last repetition (+6.7%, +12.9% and +9.3%; all p&lt;0.05), while flight time, swing time and stride length remained constant. Stride frequency decrease across repetitions approached significance (-6.8%; p=0.07). No main effect of the sprint number nor any significant interaction between sprint number and foot region was found for maximal force, mean force, peak and mean pressure (all p&gt;0.05). Center of mass vertical displacement increased (p&lt;0.01) with time, together with unchanged (both p&gt;0.05) peak vertical force and leg compression. Vertical stiffness decreased (-15.9%; p&lt;0.05) across trials, whereas leg stiffness changes were not significant (-5.9%; p&gt;0.05). Changes in root mean square activity of the three tested muscles over sprint repetitions were not significant. Conclusion: Although repeated sprinting on natural grass with players wearing soccer boots impairs their leg-spring behavior (vertical stiffness), there is no substantial concomitant alterations in muscle activation levels or plantar pressure patterns.

Time-Dependent Single-Molecule Interactions of the Platelet Integrin αIIbβ3 with Cyclic Arg-Gly-Asp and the Fibrin(ogen) γC-Dodecapeptide

AbstractAbstract 2103Both fibrinogen and fibrin bind to the platelet integrin αIIbβ3 (GPIIb-IIIa). There are at least two motifs in human fibrin(ogen) that bind to αIIbβ3: HHLGGAKQAGDV located at position 400–411 at the C-terminus of the γ chain and RGD located at position 572–574 in the Aα (or α) chain. A second RGD motif located at position 95–97 in the Aα (or α) chain may also play a role in αIIbβ3-mediated platelet adhesion on fibrin(ogen). Recent crystal structures of αIIbβ3 containing either a γ chain peptide corresponding to residues 404–411 or linear RGD-containing peptide (Springer et al., J. Cell Biol. 182:791-800, 2008) revealed that although the RGD and γ chain binding sites completely overlap, the γ chain interface with αIIbβ3 is much more extensive, implying that αIIbβ3 should bind more tightly to the γ chain peptide. To directly test this possibility, we applied single-molecule optical trap-based rupture force spectroscopy to study the interactions of RGD and HHLGGAKQAGDV with purified αIIbβ3. Experiments were performed with the cyclo(RGDFK) peptide (cRGD) and the HHLGGAKQAGDV peptide (H12) covalently attached to dextran-functionalized latex beads via their primary amines, simulating more closely the physiological situation and leaving their αIIbβ3-binding groups exposed. The cyclo(RADFK) peptide (cRAD), as well as weakly reacting surfaces containing dextran alone or albumin, were used as negative controls. We tested whether the strength and probability of formation of the αIIbβ3-ligand complex depend on the precisely controlled duration of contact between the interacting surfaces coated with the receptor and the ligand. A peptide-coated microscopic (1.9 μm) bead was trapped by the focused laser beam and repeatedly brought into contact with an αIIbβ3-coated silica pedestal (5 μm) attached to the bottom of a chamber. The repeated touching and separation of bead and pedestal were allowed to occur with a compressive force of 10–20 pN and a bead pulling speed of 0.8 μm/s. The flexible parameter was the stopping time of the oscillating bead, which corresponds to the duration of contact between the interacting surfaces. Varying the time of contact between the surface-bound peptides and αIIbβ3 from 0.01s to 2s revealed that the average binding strength for cRGD and H12 with αIIbβ3 increased to 40–50 pN until it reached a plateau at ~0.5s, indicating that the interactions were time-dependent and occurred on the time scale of tens to hundreds of milliseconds. The strength of the cRGD-αIIbβ3 binding was consistently greater than that of H12-αIIbβ3 by 15–20% at the corresponding contact times. The probability of the peptide-αIIbβ3 interaction was also time-dependent. Within an interval of contact duration of 0.01–2s, the cumulative binding probability for cRGD-αIIbβ3 bonds increased from zero up to ~35%, whereas the binding probability for H12-αIIbβ3 bonds was 21% at the same surface density of the peptides and integrin. Both values were reached at a contact duration time of ~1.0s. Importantly, because a relatively small number of interface contacts resulted in the establishment of αIIbβ3-peptide bonds during the applied range of contact time, it is likely that the majority of the measured bond rupture events resulted from the dissociation of single bonds. Thus, these data demonstrate that cRGD has a higher binding preference to αIIbβ3 compared to H12. Further, they support a hypothesis that the RGD motifs, exposed either when fibrinogen is immobilized on a surface or following its conversion to fibrin, may account for the remarkable platelet reactivity with these adhesive substrates. Disclosures:No relevant conflicts of interest to declare.

Experimental and numerical study of ball size effect on restitution coefficient in low velocity impacts

In this article, the Coefficient of Restitution (COR) and Energy Loss Percentage (ELP) of one-dimensional impacts are determined experimentally for different ball sizes using a drop test apparatus. Ball diameters range from 6 to 12 mm, made of steel and aluminum dropped on steel and aluminum sheets. Furthermore, effects of ball sizes on COR and contact time duration are studied numerically. In addition, time variation of displacement of the midpoint of sheet’s top surface and vibration of the ball’s center are investigated. This is done using a finite element model for elasto-plastic collisions. In this work, dynamic and explicit analyses have been carried out by using the LS-DYNA module of ANSYS. The numerical results are validated by the present experimental data. Moreover, the present results are compared with previous works. Results show that COR decreases as balls’ diameters increase.

Roadcast

Content sharing through vehicle-to-vehicle communication can help people find their interested content on the road. In VANETs, due to limited contact duration time and the unreliable wireless connection, a vehicle can only get the useful data when it meets the vehicle which has the exactly matching data. However, the probability of such cases is very low. To improve the performance of content sharing in intermittently connected VANETs, we propose a novel P2P content sharing scheme called Roadcast. Roadcast relaxes user's query requirement a little bit so that each user can have more chances to get the requested content quickly. Furthermore, Roadcast ensures popular data is more likely to be shared with other vehicles so that the performance of overall query delay can be improved. Roadcast consists of two components called popularity aware content retrieval and popularity aware data replacement. The popularity aware content retrieval scheme makes use of Information Retrieval (IR) techniques to find the most relevant data towards user's query, but significantly different from IR techniques by taking the data popularity factor into consideration. The popularity aware data replacement algorithm ensures that the density of different data is proportional to the square-root of their popularity in the system steady state, which firmly obeys the optimal "square-root" replication rule [6]. Results based on real city map and real traffic model show that Roadcast outperforms other content sharing schemes in VANETs.

Rigorous analysis on performance of LEO satellite ground station in urban environment

AbstractMicrosatellites in low Earth orbits (LEOs) have been in use for the past two decades. LEO satellites are used for public communication and also for scientific purposes, and the orbits vary with the type of satellites and the primary purposes. LEO scientific satellites have a variety of applications, including Earth surveillance and astronomy applications. These satellites provide opportunities for investigations for which alternative techniques are either difficult or impossible to apply. Thus, it may be expected that such missions will be further developed in the near future especially in fields where similar experiments by purely Earth‐based means are impracticable. Ground stations have to be established in order to communicate with such satellites, and the quality of communication depends on the performance of the satellite ground station, in addition to that of the satellite. Before the implementation of the ground station, analyses related to environmental factors have to be considered, especially in urban areas. Rain effects, the impact of intermodulation products, and contact time duration at low elevation angles are some of the aspects that are considered in this work and which influence the final decisions on the design of the ground station. Measurements on the ground station based on Sun flux density are described, which provide an opportunity to check the performance of the ground station. Copyright © 2007 John Wiley &amp; Sons, Ltd.

Loss and recovery of voluntary hand movements in the macaque following a cervical dorsal rhizotomy

The recovery of manual dexterity was analyzed in the macaque following a cervical dorsal root section that abolished cutaneous feedback from selected digits of one hand. Monkeys were trained to retrieve a target object from a clamp using thumb and index finger opposition. Dorsal rootlets containing electrophysiologically identified axons projecting from the thumb and index finger were then cut in two monkeys (Group 1). In four others (Group 2), additional rootlets shown to innervate the middle finger and thenar eminence were also transected. Three performance parameters were analyzed before and following the rhizotomy: 1) percentage of successful retrievals; 2) digital stratagem (the pattern of digit opposition); and 3) contact time (duration of digit contact with the object before its retrieval). During the first postoperative week, hand function was severely impaired in all monkeys. Over the following weeks, Group 1 monkeys recovered the ability to retrieve the object by opposing the index finger and thumb in >80% of trials. Group 2 monkeys also regained some function in the impaired hand: each monkey adopted a stratagem for grasping the target, using digits that were incompletely deafferented. In the terminal experiment, hand representation in the contralateral somatosensory cortex was electrophysiologically mapped to define hand deafferentation and cortical reactivation further. There was a close correspondence between the cortical map and digit use. Our data imply that the recovery of precision grip using the thumb and index finger depends on the survival of afferents innervating these digits, as well as the proliferation of their central terminals.

도마운동 유리첸코 몸 펴 공중돌기 동작의 운동학적 분석

The purpose of this study is to investigate the effective skill motion through the kinematic analysis of the Yurchenko Streched motion in new horse vaulting. The subjects in this study were 3 male gymnasts who were ranked as national athletes. After the 3D motion analysis, kinematic variables were analyzed to comparison with the difference between this study and the previous study(Yang, D. Y and Lee, C. S, 1999). As a result, the following conclusions was drawn; 1. In the board contact phase, this study showed a shorten contact time to maintain in condition highly extension of hip and hee angle than the previous study. 2. In the pre-flight phase, this study appeared more shortly flight duration time and horizontal flight displacement than the previous study. 3. In the horse contact phase, the contact duration time and horizontal displacement of COG shortened than the previous study, but appeared to the fast horizontal and vertical velocity and highly extension of shoulder an. 4. In the post-flight phase, a stable horse contact appeared to the increase of the flight duration time and the apex height during the post-flight. And it showed that these results have a stable and good landing.

Use of a fibreoptic stylet to visually evaluate tracheal intubation technique.

To compare the tracheal intubation by novices with that of instructors, we videotaped the view obtained through a fibreoptic stylet during standard tracheal intubations with a Macintosh direct laryngoscope. The duration of visualization of the vocal cords was longer during intubation by instructors than during trainee attempts. The tracheal tube contact (with pharyngeal wall) time duration was higher during intubation attempts by trainees than instructors. The quality of the image of the vocal cords through the stylet was related to these video-view parameters. Our results demonstrated that visualization of the vocal cords by direct laryngoscope and manipulation of the tracheal tube in the oral cavity were different between anaesthesia trainees and instructors, and suggested that visually monitoring the tracheal intubation procedure through a fibreoptic stylet might be useful for the education of anaesthesia trainees.

宇宙ロボットのターゲット捕捉時の運動評価 関節部の剛性の影響

To capture a target on orbit is a fundamental task for space robots. As the target doesn't have a fixed base, it might be bounced away before the capture procedure is completed. When the target is much heavier than the robot hand, the manipulator controller gain affects such dynamics. This paper uses two measures for evaluation, namely, 1) contact time (duration until the target is bounced off) and 2) final relative velocities (target velocities relative to the hand when the target drifts away) . Analytical approximations of the two measures are derived and validated through numerical simulations and hardware experiments.

Use of TNSAC in phosphate adsorption studies and relationships. Isotherm relationships and utility in the field

The studies related to the phosphate removal potential of a laboratory scale produced adsorbent, the tamarind nut shell activated carbon (TNSAC), have been partly reported in two papers by us which described the production of the various TNSAC forms, and the effects of the process variables (unrinsed and rinsed TNSAC forms and the impregnation ratio) and of the operational variables (adsorbent particle size, initial adsorbate concentration, adsorbent dose and contact time duration) on the performance evaluation of the TNSAC in adsorbing phosphates. The performance predictive models were also presented. This paper discusses the adsorption isotherm relationships and models. The applicability of the system to real field situations, and the reuse possibility and removal of the phosphate loaded adsorbent particles, have also been brought out in this paper. The isotherm plots show higher phosphate adsorptive capacity for greater equilibrium concentration values. The highest adsorptive capacity results at an impregnation ratio of 1.0 for both forms of the TNSAC and at all adsorbent doses. The adsorptive capacity is higher for the unrinsed TNSAC in comparison to the rinsed TNSAC, corresponding to the same equilibrium concentration. The rinsed TNSAC yields an isotherm model similar to the Freudlich isotherm. The unrinsed TNSAC does not yield any conventional isotherm forms, yet they have been modelled. Generalized models for predicting the adsorptive capacity have been evolved, and such models also incorporate the impregnation ratio, and the term for the adsorbent particle size. The models have indicated high correlation coefficients. When present in wastewaters, the adsorption of phosphates on the TNSAC is seen to reduce due to the preferential adsorption of other pollutants present in the wastewaters. The spent and phosphate loaded TNSAC particles are seen to be removable. Physical adsorption is seen to be the predominantly likely mechanism of phosphate adsorption on the TNSAC, which suggests the reuse possibility of the TNSAC.