High External Loads Research Articles

Effects of resistance training at different loads on inflammatory markers in young adults.

Suppressing inflammaging at an early stage in life via exercise might prevent chronic diseases later in life. The aim was to investigate the influence of resistance training at different external loads on inflammatory markers in healthy young adults. Serum was collected for basal levels of cytokines (IL-1beta, IL-6, IL-8, sTNFR1, IL-1RA, IL-10 and GM-CSF) before and after 9 weeks exercise from 36 young (22 ± 2 years) healthy subjects who were randomized to three times weekly supervised resistance training at either HImax (n = 12, 1 × 10-12 repetitions at 80% 1RM), LO (n = 12, 1 × 10-12 repetitions at 40% 1RM), or LOmax (n = 12, 1 × 10-12 repetitions at 40% 1RM preceded by 60 repetitions at 20-25% 1RM) respectively. Overall, IL-8 increased (p < 0.001) and IL-6 decreased (p = 0.001) after training, but no significant time*group interaction was found (respectively, p = 0.283 and p = 0.058 for IL-8 and IL-6). When analyzed separately, IL-8 increased significantly in HImax (p = 0.022) and LOmax (p = 0.024); and IL-6 decreased significantly in LOmax (p = 0.009) and LO (p = 0.013). No significant overall time effect was observed for sTNFR1 and IL-1RA; however, in HImax sTNFR1 (p = 0.031) and IL-1RA (p = 0.014) increased significantly, but remained unchanged in LOmax and LO. IL-1beta, IL-10 and GM-CSF levels remained undetectable in most participants. Nine weeks of resistance training-irrespective of the external load-have beneficial effects on circulating IL-8 and IL-6. In addition, training at high external load increases the anti-inflammatory cytokines sTNFR1 and IL-1RA. The results of this study show that resistance training has anti-inflammatory effects in healthy young persons and that the response of the different inflammatory mediators depends on the magnitude of the external load.

Repeated Fish Removal to Restore Lakes: Case Study of Lake Væng, Denmark—Two Biomanipulations during 30 Years of Monitoring

Biomanipulation by fish removal has been used in many shallow lakes as a method to improve lake water quality. Here, we present and analyse 30 years of chemical and biological data from the shallow and 16 ha large Lake Væng, Denmark, which has been biomanipulated twice with a 20-year interval by removing roach (Rutilus rutilus) and bream (Abramis brama). After both biomanipulations, Lake Væng shifted from a turbid, phytoplankton-dominated state to a clear, water macrophyte-dominated state. Chlorophyll a was reduced from 60–80 μg·L−1 to 10–30 μg·L−1 and the coverage of submerged macrophytes, dominated by Elodea canadensis, increased from &lt;0.1% to 70%–80%. Mean summer total phosphorus was reduced from about 0.12 to 0.07 mg·L−1 and total nitrogen decreased from 1.0 to 0.4 mg·L−1. On a seasonal scale, phosphorus and chlorophyll concentrations changed from a summer maximum during turbid conditions to a winter maximum under clear conditions. The future of Lake Væng is uncertain and a relatively high phosphorus loading via the groundwater, and the accumulation of a mobile P pool in the sediment make it likely that the lake eventually will return to turbid conditions. Repeated fish removals might be a relevant management strategy to apply in shallow lakes with a relatively high external nutrient loading.

Water Quality and Plankton Communities in Hybrid Catfish (♀ Channel Catfish,Ictalurus punctatus× ♂ Blue Catfish,Ictalurus furcatus) Ponds After Partial Fish Harvest

Twelve 0.4‐ha ponds were stocked with 10,000 hybrid catfish fingerlings in March 2015. Six ponds were partially harvested in August to remove fish larger than ∼0.57 kg. All remaining fish were removed in October and November. Partial harvest of faster‐growing fish removed ∼26% of the fish initially stocked; feeding rate (and therefore external nutrient loading) was reduced by about the same amount. However, reduced nutrient loading after partial fish harvest had no meaningful effects on water quality, phytoplankton biomass, phytoplankton and zooplankton community structure, or supplemental aeration. Lack of ecosystem change was caused by persistent internal recycling of nutrients added to the system before partial harvest and continued high (albeit reduced) external nutrient loading after partial harvest. Decisions to employ partial fish harvest to manage single‐cropped hybrid catfish ponds should be based on economic considerations and risk reduction rather than the expectation that fish biomass reduction will improve water quality.

Creep behaviors of methane hydrate coexisting with ice

A series of creep tests were carried out in order to clarify the creep behaviors of methane hydrate coexisting with ice, which may exist in the ice-bearing permafrost. Measurements on synthetic methane hydrate-ice specimens indicate that (1) higher external load will increase the initial strain and the axial strain during the whole creep test. And the creep strain rate will increase with the increase of external load; (2) the initial strain, axial strains and creep strain rate of the specimens under certain external load increase with the decrease of confining pressure; (3) temperature drop leads to the decrease of initial strain and axial strains of the specimens under certain external load. And the creep strain rate firstly increases and then decreases with the increase of temperature, due to the refreezing of dissociated water from methane hydrate; (4) the specimens run to the secondary creep stage earlier when they endure lower external load, higher confining pressure and lower temperature; (5) the specimens under higher confining pressure and lower temperature show higher failure strength.

Load-Specific Inflammation Mediating Effects of Resistance Training in Older Persons

BackgroundLittle is known about the effects of resistance training (RT) on circulating cytokines in older adults. Also, dose-response relationships remain unclear. This study investigated the impact of RT at different external loads on circulating inflammatory mediators in older community-dwelling individuals. MethodsFifty-six community-dwelling older (68 ± 5 years) volunteers were randomized to 12 weeks of supervised RT (×3/week) at either high-resistance training [8 males, 10 females, 2 × 10–15 repetitions at 80% 1 repetition maximum (RM)], low-resistance training (9 males, 10 females, 1 × 80–100 repetitions at 20% 1 RM), or mixed low-resistance training (9 males, 10 females, 1 × 60 repetitions at 20% 1 RM followed by 1 × 10–20 repetitions at 40% 1 RM). Serum was available from 51 out of 56 participants at baseline and after 12 weeks for determination of interleukin (IL)-6, IL-8, IL-10, IL-1β, soluble tumor necrosis factor receptor (sTNFR)1, granulocyte macrophage colony-stimulating factor, and IL-1 receptor antagonist (ra). ResultsTwelve weeks of RT significantly increased sTNFR1 from 2.48 ± 0.57 ng/mL to 2.58 ± 0.59 ng/mL (overall time-effect P = .033) and Log IL-8 from 0.38 ± 0.18 pg/mL to 0.53 ± 0.32 pg/mL (overall time-effect P = .007). No time X group interaction (P = .916) was observed. In males of the high-resistance training group, there was an increase in Log IL-8 (from 0.45 ± 0.16 pg/mL to 0.68 ± 0.19 pg/mL; P = .005) and IL-1ra (from 68.60 ± 24.12 pg/mL to 79.56 ± 29.07 pg/mL; P = .007). No significant changes were found for the other markers. ConclusionsOur results show that 12 weeks of supervised RT induced an overall significant increase of circulating IL-8 and sTNFR1, independently from the external load applied. We suggest that exercising until volitional fatigue is the main trigger for exercise-induced responses. However, training at high external load also increased anti-inflammatory IL-1ra in male participants, which might be beneficial in combating low-grade inflammation.

Modulated formation of lath martensite: Influence of uniaxial compressive load and transformation-induced plasticity

The austenite → martensite transformation occurring upon cooling of an FeNiCoMo alloy, similar to commercial FeNiCoMo maraging steels, thereby forming lath martensite, was investigated by dilatometry with regard to the influence of an externally applied compressive load on the peculiar transformation behavior in this system, which exhibits a step-wise mode of transformation upon slow cooling, as shown recently. Temporary, external loading during isothermal interruption of the continuous cooling at different stages of the transformation revealed a decreasing degree of plastic deformation proportional with the decreasing amount of retained austenite, implying that the plastic deformation is predominantly accomplished within the austenite phase. Upon resuming the cooling, the step-wise transformation was found to be unaffected. Application of a constant, comparatively high external load during continuous cooling caused a step-wise length decrease in the temperature range of the transformation instead of the step-wise length increase observed for the martensitic transformation in absence of an external load. The plastic deformation happening during the transformation occurs also for loads below the yield limit of pure austenite. This genuine transformation-induced plasticity was ascribed to the generation of mobile dislocations within the austenite upon the formation of martensite, thereby enabling plastic deformation in addition to the intrinsic deformation induced by the load for a specimen in the absence of transformation. Because the transformation into martensite also during loading takes place in a step-wise manner, the generation of these mobile dislocations occurs step-wise too, thus leading to the observed step-wise plastic deformation and corresponding step-wise length decrease during the transformation.

Swimming of a Non-Flagellated Bacterium by a Non-Rotary Molecular Motor

Free-swimming bacteria commonly exploit a system of propeller-like appendages called flagella to generate propulsion, typically attached to rotary molecular motors. In harsh contrast, the helically-shaped and minimalistic genus Spiroplasma lacks such a system but is able to swim anyway. This is achieved by a linear motor generating pairs of kinks propagating down the length of the cell body. The motor itself consists of a contractile chain of approx. 600 identical proteins spanning the entire length of the cell. Kinks are generated by a concerted spread of conformational changes of the motor's subunits within approx. 100ms, always starting at the same end of the cell.Here, we use object-adapted optical trapping and shape-tracking to characterize the dynamics of the swimming pattern of single cells under different metabolic and chemical conditions. Further, we demonstrate a force sensitivity of the motor by optically mimicking micro-environments with different elasticity. The results suggest that the motor performs better under high external loads, i.e., in stiff environments. We present a rate model describing the subsequent and highly cooperative conformational switching of the chain's subunits, allosterically triggered by binding of an effector ligand. This is a further step to draw a complete picture of the maybe simplest principle of autonomous locomotion possible on the single cell level which might have an important impact on constructing bio-inspired, autonomous micro-machines.

A new model analysis approach for bridge-type amplifiers supporting nano-stage design

This paper presents a new analysis method for bridge-type amplifiers by incorporating the effect of external loads, and establishes a theoretical model to predict the input/output displacement amplification ratio based on elastic beam theory. The new analytical model indicates that the displacement amplification ratio of the bridge-type amplifiers decreases significantly in the presence of external loads, and its changing rate increases with higher external loads. The analysis method is then applied to the modeling and design of a bridge-type-amplifier based nano-manipulating stage, where the guiding mechanism acts as the external load of the bridge-type amplifiers. It is shown that the new analysis method can derive more accurate model of the nano-stage, which is further verified by the finite element analysis (FEA) results. The proposed method offers a new look into the analysis and design of flexure based nano-stages for real applications.

Efficient Models of Three-Dimensional Tilting Pad Journal Bearings for the Study of the Interactions Between Rotor and Lubricant Supply Plant

In many industrial applications, tilting pad journal bearings (TPJBs) are increasingly used because they are very suitable both for high-speed and high external loads. Their study is fundamental in rotating machines and a compromise between accuracy and numerical efficiency is mandatory to achieve reliable results in a reasonable time. This paper mainly focuses on the development of efficient three-dimensional (3D) models of TPJBs, in order to contemporaneously describe both the rotor dynamics of the system and the lubricant supply plant in long simulations (from the initial transient phase to the steady-state condition). Usually, these two aspects are studied separately, but their interactions must be considered if an accurate description of the whole system is needed. The proposed model architecture considers all the six degrees-of-freedom (DOFs) between supporting structures and rotors and can be applied to different types of TJPB layout with different lubricant supply plants. In this research activity, the whole model has been developed and validated in collaboration with Nuovo Pignone General Electric S.p.a. which provided the required technical and experimental data.

High‐Performance Epoxy Nanocomposites Reinforced with Three‐Dimensional Carbon Nanotube Sponge for Electromagnetic Interference Shielding

Light‐weight and high‐performance electromagnetic interference (EMI)‐shielding epoxy nanocomposites are prepared by an infiltration method using a 3D carbon nanotube (CNT) sponge as the 3D reinforcement and conducting framework. The preformed, highly porous, and electrically conducting framework acts as a highway for electron transport and can resist a high external loading to protect the epoxy nanocomposite. Consequently, a remarkable conductivity of 148 S m−1 and an outstanding EMI shielding effectiveness of around 33 dB in the X‐band are achieved for the epoxy nanocomposite with 0.66 wt% of CNT sponge, which is higher than that achieved for epoxy nanocomposites with 20 wt% of conventional CNTs. More importantly, the CNT sponge provides a dual advantage over conventional CNTs in its prominent reinforcement and toughening of the epoxy composite. Only 0.66 wt% of CNT sponge significantly increases the flexural and tensile strengths by 102% and 64%, respectively, as compared to those of neat epoxy. Moreover, the nanocomposite shows a 250% increase in tensile toughness and a 97% increase in elongation at break. These results indicate that CNT sponge is an ideal functional component for mechanically strong and high‐performance EMI‐shielding nanocomposites.

Velocity-Based Training of Lower Limb to Improve Absolute and Relative Power Outputs in Concentric Phase of Half-Squat in Soccer Players

The power production is force-velocity related. We hypothesized that speed-based training of lower limb using half-squat can lead to absolute and relative power improvements in concentric movement with the same external load. One group of 19 soccer players (age = 24.4 years, SD = 3.7 years) participated in a pretest-posttest power training protocol, consistent in 2 training sessions per week during 10 weeks, targeted to work the leg power by performing half-squat with a fixed external load (mean = 71.7, SD = 5.4) at 65% of 1 repetition maximum. Measurements of power (absolute [in watt] and relative [in watt per kilogram]), force (in newton), and velocity (in meter per second) (mean and peak) were made from a concentric movement of a half-squat exercise with a fixed external load. The training protocol increased relative power (mean = 47.5, SD = 47.5, p < 0.001) and absolute power (mean = 169.2, SD = 95.5, p < 0.001). Also, number of repetitions (mean = 2.9, SD = 2.4, p < 0.01), force (mean = 66.6, SD = 36.7, p < 0.001), and velocity (mean = 0.1, SD = 0.1, p < 0.001) were increased. However, only improved velocity was related to the changes in absolute (r = 0.939, p < 0.001) and relative (r = 0.757, p < 0.001) power. The speed-based training combined with moderate to high external load can lead to an improvement of absolute and relative power in concentric phases of half-squat in soccer players. This could be important for improving the performance of the players in the field.

Experimental Investigation on Shock Mechanical Properties of Red Sandstone under Preloaded 3D Static Stresses

Triaxial impact mechanical performance experiment was performed to study the mechanical properties of red sandstone subjected to three-dimensional (3D) coupled static and dynamic loads, i.e., three confining pressures (0, 5, and 10 MPa) and three axial pressures (11, 27, and 43 MPa). A modified 3D split Hopkinson pressure bar testing system was used. The change trend in the deformation of red sandstone and the strength and failure modes under axial pressures and confining pressures were analyzed. Results show that, when the confining pressure is constant, the compressive strength, secant modulus, and energy absorbed per unit volume of red sandstone initially increases and subsequently decreases, whereas the average strain rate exhibits an opposite trend. When the axial pressure is constant, both the compressive strength and secant modulus of red sandstone are enhanced, but the average strain rate is decreased with increasing confining pressure. The energy absorbed per unit volume is initially increased and subsequently decreased as the confining pressure increases. Red sandstone exhibits a cone-shaped compression–shear failure mode under the 3D coupled static and dynamic loads. The conclusions serve as theoretical basis on the mechanical properties of deep medium-strength rock under a high ground stress and external load disturbance condition.

Competitive tradeoffs between working memory and attention: An fMRI approach

Previous research has highlighted a close relationship between working memory (WM; i.e., the short-term maintenance and manipulation of internal information) and attention (i.e., the selective processing of a limited amount of external information). This reciprocity between WM and attention can be thought of as two sides of the same coin, such that WM (internal) and visual attention (external) could draw from, and thus compete for, a common cognitive resource. To examine the behavioral and neural characteristics of this interaction, we acquired fMRI data during a dual-task paradigm that simultaneously and systematically taxed both internal (WM) and external (visual) attentional load. Participants remembered one or two images (i.e., low vs. high internal load) for a delayed match-to-sample task. During the delay, participants performed a series of visual searches for target items that were either highly distinct from or similar to visual distractors (i.e., low vs. high external load). Behavioral data revealed that the impact of internal load on memory performance was inversely related to the impact of external load on search performance, suggesting that the effective processing of cognitive load in one domain increased susceptibility to load in the other domain. For example, for participants whose search performance was less affected by high external load, memory performance was more impaired by high internal load. Neural activity also revealed robust interactions between the two domains, such that parietal and temporal regions were differentially recruited to manage internal load in the face of low and high external load, respectively. Moreover, individual differences in independent measures of visual WM capacity and visual search efficiency modulated these behavioral and neural tradeoffs between internal and external attention. Collectively, these findings support the idea of WM and visual attention as competitive and interdependent constructs, whose interactions are processed by a network of fronto-temporo-parietal substrates. Meeting abstract presented at VSS 2015

Impacts of fish on phosphorus budget dynamics of some SA reservoirs: evaluating prospects of ‘bottom up’ phosphorus reduction in eutrophic systems through fish removal (biomanipulation)

Data on fish standing stocks in 7 South African reservoirs were used to assess prospects of reducing in-lake amounts of total phosphorus (TP) through remedial biomanipulation – the removal of fish to deplete internal stocks of biomass-incorporated TP and especially to restrict enhancement of TP availability through internal ‘bottom up’ recycling by fish. Literature-derived conversion functions were used to estimate the quantity of TP stored in fish biomass, recycled by fish through excretion, and released from bottom sediments through carp and catfish bioturbation. This provided a quasi mass-balance assessment of these contributory influences of fish on TP budgets of reservoirs ranging from mesotrophy to hypertrophy in trophic status (annual mean TP levels of 0.04–0.51 mg/ℓ). Absolute contributions of fish were inevitably related directly to reservoir-specific fish stock abundance, both total-fish and coarse-fish biomass levels which increased with trophic status, generating parallel absolute increases in TP sinks and internal TP loading fluxes. On overall average, total fish stock sequestered 2.2 kg TP/ha in biomass, recycled 13.8 kg TP/ha/yr through excretion, and mobilized 8.0 kg TP/ha/yr through sediment bioturbation. Average values relative to external loadings in 5 reservoirs amounted to 3.8% (biomass), 22.8% (excretion) and 11.8% (bioturbation), totalling 38.4%. Most pertinently, the relative importance of fish in reservoir TP budgets declined progressively with rising trophic status, with corresponding averages less than half (1.4, 8.7 and 5.4%, total = 15.4%) in 3 hypertrophic reservoirs (&gt; 0.10 mg TP/ℓ). While total fish eradication plausibly reduces average internal phosphorus by some 40% relative to external load, the corresponding average reduction in hypertrophic reservoirs in greatest need of nutrient reduction is far less (~ 15%). ‘Bottom-up’ bioremediation accordingly offers little help in the management of nutrient-enriched reservoirs, and is essentially futile where high external nutrient loading persists.Keywords: biomanipulation, biomass sinks, bioturbation, eutrophication management, excretion, fish, phosphorus, recycling, reservoir ecosystems

High-Intensity Training and Salivary Immunoglobulin A Responses in Professional Top-Level Soccer Players: Effect of Training Intensity

Owen, AL, Wong, DP, Dunlop, G, Groussard, C, Kebsi, W, Dellal, A, Morgans, R, and Zouhal, H. High-intensity training and salivary immunoglobulin A responses in professional top-level soccer players: Effect of training intensity. J Strength Cond Res 30(9): 2460-2469, 2016-This study aimed (a) to test the hypothesis that salivary immunoglobulin A (s-IgA) would vary with training intensity sessions (low-intensity [LI] vs. high-intensity sessions [HI]) during a traditional training program divided into 4 training periods and (b) to identify key variables (e.g., GPS data, rating of perceived exertion [RPE], and training duration), which could affect s-IgA. Saliva samples of 10 elite professional soccer players were collected (a) before the investigation started to establish the baseline level and (b) before and after each 4 training sessions (LI vs. HI). Training intensity was monitored as internal (through heart rate responses and RPE) and external (through GPS) loads. High-intensity sessions were associated with higher external load (GPS) and with higher RPE. Baseline and pretraining s-IgA did not differ between the 4 training sessions both for HI and LI. Post-training s-IgA were not different (in absolute value and in percentage of change) between HI and LI sessions at the first 3 periods. However, at the fourth period, s-IgA concentration for HI session was significantly lower (p ≤ 0.05) than the LI session. The percentage change between s-IgA post-training and s-IgA baseline concentrations differ significantly (p ≤ 0.05) between HI and LI training sessions. Significant correlations between s-IgA and training intensity were also noted. High-intensity soccer training sessions might cause a significant decrease in s-IgA values during the postexercise window as compared with LI sessions. This study encourages coaches to monitor s-IgA in routine, particularly during HI training periods, to take precautions to avoid upper respiratory tract infection in highly trained soccer players.

High-Speed, Radiation-Tolerant Laser Drivers in 0.13 &lt;formula formulatype="inline"&gt;&lt;tex Notation="TeX"&gt;$\mu$&lt;/tex&gt;&lt;/formula&gt;m CMOS Technology for HEP Applications

The gigabit laser driver (GBLD) and low-power GBLD (LpGBLD) are two radiation-tolerant laser drivers designed to drive laser diodes at data rates up to 4.8 Gb/s. They have been designed in the framework of the gigabit-transceiver (GBT) and versatile-link projects to provide fast optical links capable of operation in the radiation environment of future high-luminosity high-energy physics experiments. The GBLD provides laser bias and modulation currents up to 43 mA and 24 mA, respectively. It can thus be used to drive vertical cavity surface emitting laser (VCSEL) and edge-emitting laser diodes. A pre-emphasis circuit, which can provide up to 12 mA in 70 ps pulses, has also been implemented to compensate for high external capacitive loads. The current driving capabilities of the LpGBLD are 2 times smaller that those of the GBLD as it has been optimized to drive VCSELs in order to minimize the power consumption. Both application-specific integrated circuits are designed in 0.13 μm commercial complementary metal-oxide semiconductor technology and are powered by a single 2.5 V supply. The power consumption of the core circuit is 89 mW for the GBLD and 55 mW for the LpGBLD.

The Unusual Mechanical Evolution of Biodegradable Double Hydrogen Bonding Strengthened Hydrogels in Response to pH Change

Conventionally, biodegradable hydrogels end up with quick disintegration and consequently fail to bear external loading after degradation. Here, a biocleavable high‐strength hydrogel prepared by copolymerization of 2‐vinyl‐4,6‐diamino‐1,3,5‐triazine (alkali active H‐bonding monomer), 3‐acrylamidophenylboronic acid (acid active H‐bonding monomer), oligo(ethylene glycol) methacrylate, and crosslinker N,N′‐bis(acryloyl)cystamine is reported. The hydrogel is shown to be degraded after the disulfide bonds in the chemical crosslinkers are broken down in a reducible medium. Remarkably, the degraded hydrogel evolves into supramolecular network, which is strengthened by diaminotriazine–diaminotriazine and phenylboronic acid–phenylboronic acid dual H‐bonded physical crosslinks despite the loss of chemical crosslinking. It is demonstrated that over a broad pH range, the degraded hydrogels are able to retain macroscopic integrity and withstand high external loading due to the existence of at least one kind of hydrogen bonding crosslinking. This biodegradable double hydrogen bonding strengthened hydrogel may push forward the research on a new type of high‐strength hydrogels. image

Eccentric exercise: mechanisms and effects when used as training regime or training adjunct

The aim of the current review is to discuss applications and mechanism of eccentric exercise in training regimes of competitive sports. Eccentric muscle work is important in most sports. Eccentric muscle contractions enhance the performance during the concentric phase of stretch-shortening cycles, which is important in disciplines like sprinting, jumping, throwing, and running. Muscles activated during lengthening movements can also function as shock absorbers, to decelerate during landing tasks or to precisely deal with high external loading in sports like alpine skiing. The few studies available on trained subjects reveal that eccentric training can further enhance maximal muscle strength and power. It can further optimize muscle length for maximal tension development at a greater degree of extension, and has potential to improve muscle coordination during eccentric tasks. In skeletal muscles, these functional adaptations are based on increases in muscle mass, fascicle length, number of sarcomeres, and cross-sectional area of type II fibers. Identified modalities for eccentric loading in athletic populations involve classical isotonic exercises, accentuated jumping exercises, eccentric overloading exercises, and eccentric cycle ergometry. We conclude that eccentric exercise offers a promising training modality to enhance performance and to prevent injuries in athletes. However, further research is necessary to better understand how the neuromuscular system adapts to eccentric loading in athletes.

Realization and thermal performance analysis of liquid nitrogen based 80 K Cryo-Target system for space simulation of meteorological payloads

Liquid nitrogen based Cryo-target system need to be used in thermo-vacuum chamber to simulate on-orbit environments of meteorological payloads. For a number of reasons it is essentially important to quantify the thermal performance of CT system prior to the actual tests of meteorological payloads. In this paper we present thermal performance of an efficient closed loop liquid nitrogen circulated blistered type embossed CT system inside thermovacuum chamber. We discuss important experiments, tests and their results that were carried out for the performance optimization of CT system. The optimized CT systems with space qualified conductive black painted aluminum honeycomb mounted on it were successfully used for Met payloads of INSAT 3D during TVP tests. The heat load handling capacity of closed loop flat plate CT system in thermo-vacuum chamber is analytically investigated. It is concluded that a closed loop CT system is better for low temperature and high external heat load requirements.

Deflection model for robotic friction stir welding

Purpose – This paper aims to present a deflection model to improve positional accuracy of industrial robots. Earlier studies have demonstrated the lack of accuracy of heavy-duty robots when exposed to high external forces. One application where the robot is pushed to its limits in terms of forces is friction stir welding (FSW). This process requires the robot to deliver forces of several kilonewtons causing deflections in the robot joints. Especially for robots with serial kinematics, these deflections will result in significant tool deviations, leading to inferior weld quality. Design/methodology/approach – This paper presents a kinematic deflection model, assuming a rigid link and flexible joint serial kinematics robot. As robotic FSW is a process which involves high external loads and a constant welding speed of usually below 50 mm/s, many of the dynamic effects are negligible. The model uses force feedback from a force sensor, embedded on the robot, and predicts the tool deviation, based on the measured external forces. The deviation is fed back to the robot controller and used for online path compensation. Findings – The model is verified by subjecting an FSW tool to an external load and moving it along a path, with and without deviation compensation. The measured tool deviation with compensation was within the allowable tolerance for FSW. Practical implications – The model can be applied to other robots with a force sensor. Originality/value – The presented deflection model is based on force feedback and can predict and compensate tool deviations online.