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The article focuses on the aging and degradation of polymer foil sheets by analyzing weather impacts on light polymer foil used for additional roofing underlays in sloping roofs. The author relies on tests for specific material properties exposed to various weather conditions. Inspecting effects of different types of weather, he concludes that solar radiation is the most impactful factor on the overall state and degree of material degradation. [ABSTRACT FROM AUTHOR]

Certain elements of the mechanisms behind the deflagration-to-detonation transition (DDT) of high explosives (HE) in weak confinement are still poorly understood. At Los Alamos National Laboratory, we have developed a piston-impact-ignited DDT experiment to promptly initiate the one-dimensional compressive burning of a column of weakly confined HE in order to explore and observe how the Type I DDT process in weak confinement varies from what has been well described when strong metal confinement is used. The experiment consists of a smokeless-powder-propellant gun and an HE-sample holder. The smokeless-powder gun is used to accelerate a right-circular-cylindrical projectile to impact and ignite a column of weakly confined HE held in the test-sample holder. The gun itself houses two diagnostics: a custom single/dual-channel optical encoder used to continuously track the position of the projectile during the informative majority of the test, and a piezoelectric pressure sensor used to observe the pressure of the propelling gas in the bore of the gun. Multiple other diagnostics can be successfully fielded on each test including high-speed video, streak imaging, and an in-house four-channel pyrometer. To study the DDT process, we completed a test series of more than 25 successful impact-ignited tests involving confined HE using this new experiment. The majority of the impact velocities observed in this series ranged from ∼120-160 meters per second, usually using a projectile mass of ∼19 grams. Results from the test series showed interesting behavior pertaining to Type 1 DDT of both pressed-pellet and hand-tamped-powder PETN samples. Among the most notable results from the test series was the recording of a Type 1 DDT of a column of PETN powder. The sample was hand-tamped to 75% theoretical maximum density (TMD) in an annealed-polycarbonate-confinement tube and impacted by a 19.8g projectile traveling 154 m/s. Two high-speed video cameras (Phantom v2512 color @ 271,000 images per second (ips), and Phantom v710 monochromatic @ 990,000 ips) captured all stages of the experiment including: impact, generation of compaction wave, initiation of a 1D compressive burn, and the transition from deflagration to detonation. [ABSTRACT FROM AUTHOR]

A test series of PVC windows with different configurations were carried out under laboratory conditions. Thickness of PVC profiles and design of an insulating glass unit were the variable parameters, while the hardware and overall specimen dimensions stay the same. Tests were performed in several stages: only under wind load (according to the standard method); only under temperature load and under the combination of wind and temperature loads (according to a specially developed method). During the tests a sag of window profile elements were measured using linear displacement sensors. The studies have revealed a number of factors and phenomena which are not currently considered in window structures design and strength analysis: a significant influence of PVC profile stiffness on a mullion deflection, the influence of insulating glass unit stiffness on casement window elements deformation, and the influence of hinge joints mobility on casement displacement. It was established, that not only a window mullion, but also a frame should be considered as the element under calculation in the case of wind and temperature loads simultaneous action. The seal failure is observed exactly in the place where the sash adjoins the window frame. These two elements have quite different stiffens, which leads to different deflections and, as consequents, to gaps formation, while the mullion deflection is commensurable with those of the sash and their joint stays airtight. The considered phenomenon must be taken into account when developing the design solution of window hardware (pitch and locations of fixing points). [ABSTRACT FROM AUTHOR]

Some recycled plastics would provide the mechanical, thermal, and optical properties to replace virgin materials in some applications, but they are not used because of their odor. The reason for the unpleasant odour of post-consumer recyclates is that they are containing volatile compounds from their former applications, which also may have undergone degradation in the recycling steps, like residues from food or drinks which were stored in the package. We found that a reduction of such emissions is possible in the melt processing step of the recycling in a previous work but saw a big influence of processing parameters as the material will also further degrade in this step [1]. Therefore, the aim of this work was to investigate the reduction of the emissions in a co-rotating twin screw extruder with vacuum degassing, with an emphasis on different temperature profiles and screw configurations. Previous tests have shown that the temperature is a major factor to reduce the emissions, but around 250°C degradation effects have a negative influence. Therefore, another test series was processed to validate this effect and to find the optimal temperature settings for the process. The untreated recyclate was processed with different screw configurations. The emissions of all the compounds were determined with gas chromatography according to VDA 277. Further, mechanical characterization with tensile and notched impact tests was carried out to investigate the effects of the different processing parameters on the materials behavior. In addition, also the Oxidation Induction Time was determined to check how much of the stabilizer is left in the material. The results were compared to find the best settings for the process. The first tests with different screws show that emissions can be reduced over 70% with the right screw configuration and process settings. [ABSTRACT FROM AUTHOR]

Currently, there are no series applications of thermoset and rubber manufactured by multicomponent injection molding. For the reasons that the material behavior of thermoset and rubber is suitable for technical applications, mainly for high temperatures and chemical aggressive surrounding, as well as that their curing behavior is very similar in injection molding, the processing of multicomponent injection molding using reactive materials (thermoset and rubber) were analyzed. In present study, factors determining compound properties, the adhesive strength of the compounds, were investigated. The results show the practicality to create thermoset-rubber compounds with multicomponent injection molding technology and reveal important influencing variables for the compound properties and in the special case of the adhesive strength of the compounds. [ABSTRACT FROM AUTHOR]

Due to their favourable spectrum of properties, thermosets are becoming increasingly important in the course of growing electrification and increasing power density in automotive construction. As a result of the cross-linking, thermosets exhibit almost constant mechanical properties over a wide temperature range. The often used high filler content of approx. 80 wt.% also leads to an extremely low shrinkage level, which means that close tolerances can be achieved. Thermosets have a similar coefficient of thermal expansion to steel and no characteristic creep behaviour, so that thermosets are an ideal material for screwing. Up to now, there are no guidelines for the design of screw-in tubes and direct screw connections in thermoset moulding compounds. The design is currently based on the guidelines for thermoplastics, whose material behaviour cannot be completely transferred to thermosets. This leads to the fact that extensive validation test series are necessary in order to guarantee sufficient process reliability. The aim of a public research project is to develop a material-optimised screw-in tube geometry for direct screw connections in thermosets and to gain knowledge about the material and failure behaviour. For this purpose, the influence of characteristic process parameters and of the tube geometry on the fastening reliability is statistically analysed. The quality parameters used for this are the screw connection parameters, installation and stripping torque, as indicators for the screw ability and reproducibility of the screw connection. Furthermore, the time-dependent decrease of the pre-load force is investigated in order to evaluate the screw connection reliability. With a reduced processing temperature, the screwing security can be further optimised and the quality-determining preload relaxation can be further reduced. With regard to the geometry design, the choice of the core hole diameter and the screw-in length has the greatest influence on the screw connection reliability. Increasing the outer diameter can also improve pre-load relief and enable joint repair, thus extending the product life cycle. [ABSTRACT FROM AUTHOR]

Successful development of space fission systems will require an extensive program of affordable and realistic testing. In addition to tests related to design/development of the fission system, realistic testing of the actual flight unit must also be performed. Testing can be divided into two categories, non-nuclear tests and nuclear tests. Full power nuclear tests of space fission systems are expensive, time consuming, and of limited use, even in the best of programmatic environments. If the system is designed to operate within established radiation damage and fuel burn up limits while simultaneously being designed to allow close simulation of heat from fission using resistance heaters, high confidence in fission system performance and lifetime can be attained through a series of non-nuclear tests. Non-nuclear tests are affordable and timely, and the cause of component and system failures can be quickly and accurately identified. MSFC is leading a Safe Affordable Fission Engine (SAFE) test series whose ultimate goal is the demonstration of a 300 kW flight configuration system using non-nuclear testing. This test series is carried out in collaboration with other NASA centers, other government agencies, industry, and universities. If SAFE-related nuclear tests are desired, they will have a high probability of success and can be performed at existing nuclear facilities. The paper describes the SAFE non-nuclear test series, which includes test article descriptions, test results and conclusions, and future test plans. [ABSTRACT FROM AUTHOR]

This paper presents the results of a series of exploratory tests of the developed recurrent neural networks (RNN) architecture xMANN (external memory memory-augmented neural network). The performance of RNN architecture xMANN was evaluated by comparing the results of the test series with the results obtained using RNN control architecture LSTM (long short-term memory) Tests were conducted with different initial conditions: composition of input data; option of educational trajectory sampling; size of embedding vector for events; size of 'window' in embedding layer training; number of iterations in embedding layer training; number of batches in RNN training; number of epochs in RNN training; Percentage of training examples; Fraction of trajectories used for cross-validation of RNN training epoch results. The result was a configuration of the raw data and hyperparameters of recurrent neural networks training and features of its architecture such that they enabled the prediction of the optimal learning trajectory with the maximum value of the accuracy function and the minimum value of the loss function. The xMANN architecture showed an advantage over the LSTM architecture in predicting the optimal educational trajectory accuracy for all series of experiments. On average, the loss function value for xMANN is 0.34 lower than LSTM for all series of trials, the 'area under curve' indicator is on average 0.07 higher than LSTM. [ABSTRACT FROM AUTHOR]

Due to their ability to form fusion bonds, composites with thermoplastic matrix offer new opportunities to assemble complex structures with a multitude of single components. By combining the laser-assisted Thermoplastic Automated Fiber Placement process (TP-AFP) with the thermoforming technology, a time-efficient process chain for producing hollow skin-stiffener structures was developed. Removable core systems are inserted into the cavity of thermoformed omega profiles for subsequent TP-AFP processing of skin layers to the top of the flanges. This enables in-situ joining between the flanges of the thermoformed profile and the skin layers without the need for other joining technologies or supplementary bonding materials. Mode I interlaminar fracture toughness tests were conducted to evaluate the performance of this joining strategy. Partially fiber-placed and thermoformed test specimen were produced by the combined TP-AFP/thermoforming process transferring the developed joining strategy to coupon level. In addition, fiber-placed specimens were manufactured with and without additional processing in a press to act as a reference. The effects of different cooling rates during production of the test panels on the crystallinity were determined by Differential Scanning Calorimetry (DSC). The mode I interlaminar fracture toughness test results show that partially fiber-placed and thermoformed test specimen have a comparable level of resistance against delamination as entirely fiber-placed or thermoformed test specimen. The similar amount of crystallinity of these test panels, determined by an introduced crystallinity ratio (CR), correlates with the mode I interlaminar fracture toughness test results and indicates a low influence of the developed joining strategy on the crystallinity amount at the joint zone. [ABSTRACT FROM AUTHOR]

Successful development of space fission systems requires an extensive program of affordable and realistic testing. In addition to tests related to design/development of the fission system, realistic testing of the actual flight unit must also be performed. If the system is designed to operate within established radiation damage and fuel burn up limits while simultaneously being designed to allow close simulation of heat from fission using resistance heaters, high confidence in fission system performance and lifetime can be attained through a series of non-nuclear tests. The Safe Affordable Fission Engine (SAFE) test series, whose ultimate goal is the demonstration of a 300 kW flight configuration system, has demonstrated that realistic testing can be performed using non-nuclear methods. This test series, carried out in collaboration with other NASA centers, other government agencies, industry, and universities, successfully completed a testing program with a 30 kWt core, Stirling engine, and ion engine configuration. Additionally, a 100 kWt core is in fabrication and appropriate test facilities are being reconfigured. This paper describes the current SAFE non-nuclear tests, which includes test article descriptions, test results and conclusions, and future test plans. [ABSTRACT FROM AUTHOR]

Keeping the reflector component clean is a big challenge in the solar energy industry. In order to optimize cleaning strategies, a precise and repeatable experimental procedure, which is capable of replicating a sequential soiling process under laboratory condition is required. An artificial soiling method and a test-rig with a glass drop-tube were designed and its performance was tested. The test-rig provides soiled samples, which are up to 16.3 % "under-soiled". Specular reflectivity differences on soiled samples are smaller than 5% reflectance. Sequential soiling tests, with a target MDD∼0.25 g/m2 were repeated up to 10 times. This represents an average daily soiling load globally. The current method can be further optimized. [ABSTRACT FROM AUTHOR]

The paper describes the application concept of additive manufactured dies to support the robot-based incremental sheet metal forming process ('Roboforming') for the production of sheet metal components in small batch sizes. Compared to the dieless kinematic-based generation of a shape by means of two cooperating industrial robots, the supporting robot models a die on the back of the metal sheet by using the robot-based fused layer manufacturing process (FLM). This tool chain is software-defined and preserves the high geometrical form flexibility of Roboforming while flexibly generating support structures adapted to the final part's geometry. Test series serve to confirm the feasibility of the concept by investigating the process challenges of the adhesion to the sheet surface and the general stability as well as the influence on the geometric accuracy compared to the well-known forming strategies. [ABSTRACT FROM AUTHOR]

One of the ways to save raw materials and energy resources is the introduction of non-destructive testing at precast concrete factories as an integral part of comprehensive quality control. This article discusses non-destructive methods for determining the strength of concrete, describes and presents the results and analysis of studies. Two main test methods were identified and compared - drilling and ultrasonic methods. Including used a comprehensive test method. The procedure involved a random selection of cubes for each test series. Each type of test was subjected to 10 cubes. Impact, indentation and ultrasonic tests were carried out in accordance with the existing Code. The drilling method was defined as new. According to the test results, graphs are built. Analysis of the graphs obtained gives a more complete picture of the strength properties of materials and structures. Complex tests allow us to assume the further nature of the behavior of materials and structures under the influence of loads in comparison with the case when only one test method is used. One of the ways to save raw materials and energy resources is the introduction of non-destructive testing at precast concrete factories as an integral part of comprehensive quality control. [ABSTRACT FROM AUTHOR]

Modern high-performance materials such as fiber-reinforced plastics are currently indispensable in various industries. Despite higher melt viscosity, recent developments allow the use of thermoplastic materials as a matrix material. Using the pultrusion process, unidirectional thermoplastic tapes can be produced continuously. The materials used in the production of these tapes undergo a quality assurance process in their production. Tapes, however, are often only tested destructively or optically. It would therefore be desirable to have a non-destructive testing method that can detect cracks, inclusions and changes in the impregnation quality quickly and without contact. To determine the impregnation quality, four CFRP tapes with slightly different degrees of impregnation were examined using slanted air-coupled ultrasound transmission. The test specimens were scanned in meandering form and all data were evaluated by means of various specially programmed analysis programs. A tape was arbitrarily selected as OK-Tape and the maximum/minimum amplitude, the mean of the amplitudes and the standard deviations of the entire C-Scan were defined as standard. With an automated evaluation software, quality points could be given for each tape, which were calculated depending on the data of the OK-tape. Using this method, small differences in the total area of the tapes as well as local inhomogeneity, such as holes, were detected. This procedure demonstrates how small differences in tape quality can be detected, although a calibration to an OK-tape is required. [ABSTRACT FROM AUTHOR]

Cast polyamides, which are synthesized through anionical polymerization in a forming mold, have a high molecular weight compared to polyamides synthesized through polycondensation. However, high amounts of wastes (e.g. unusable sprues, post-processing wastes) occur with this production method. Because of this and due to the high molecular weight of the cast polyamide, compounding of the wastes and a further processing via methods like thermoforming is a potential approach for the recycling of polyamide wastes. However, when the polyamide wastes are recycled in a twinscrew extruder, the remaining catalyst, which is embedded within the wastes, can lead to a degradation of the polyamide chains. This degradation results in molecular weights respectively melt viscosities, which are suitable for processing via injection molding but not suitable for methods like thermoforming, for which high viscosities are necessary. In this work, cast polyamide wastes were compounded in a twin-screw extruder with additives to obtain maximum viscosities. We considered (mono- and di-)carboxylic acids, which act as catalyst catchers, as well as different additives, which increase the molecular weight, (linear chain extenders and multifunctional polymeric backbones). After the compounding, rheological measurements were conducted to examine the degree of the viscosity increase and thermal measurements to estimate a processing window for thermoforming. The rheological measurements showed that the increase is strongly dependent on the waste batches, which were used for the respective test series. However, the thermal properties were not influenced through the polymer modification. Overall, viscosities could be reached, which were high enough to produce semi-finished parts out of the compounds. Additionally, thermoformed polyamide parts with exact forming shape as well as constant wall thicknesses were realized. [ABSTRACT FROM AUTHOR]

The Safe Affordable Fission Engine (SAFE) test series addresses Phase 1 Space Fission Systems issues in particular non-nuclear testing and system integration issues leading to the testing and non-nuclear demonstration of a 400-kW fully integrated flight unit. The first part of the SAFE 30 test series demonstrated operation of the simulated nuclear core and heat pipe system. Experimental data acquired in a number of different test scenarios will validate existing computational models, demonstrated system flexibility (fast start-ups, multiple start-ups/shut downs), simulate predictable failure modes and operating environments. The objective of the second part is to demonstrate an integrated propulsion system consisting of a core, conversion system and a thruster where the system converts thermal heat into jet power. This end-to-end system demonstration sets a precedent for ground testing of nuclear electric propulsion systems. The paper describes the SAFE 30 end-to-end system demonstration and its subsystems. [ABSTRACT FROM AUTHOR]

The article presents the results of research in the field of reinforced concrete screw piles installation. One of the possible ways to reduce the values of torques during the construction of the cavity, for the subsequent formation of the screw piles body, is proposed. In the laboratory, a polyethylene terephthalate coating was used, which is sufficiently strong to tear and shock, and is also resistant to aggressive chemical influences. During the research, it was found that such a coating reduces the friction of reinforced concrete piles with the ground and can be used as a permanent form for the manufacture of permanent reinforced concrete piles. Also, the use of pile coatings will significantly reduce labor costs both at the manufacturing stage and at the stage of installing prefabricated monolithic reinforced concrete screw piles. [ABSTRACT FROM AUTHOR]

The Detrended Fluctuation Analysis (DFA) is a method of nonlinear dynamics usually used to the characterization of non-stationary signals. Particularly, this technique provides information about correlations of heartbeat intervals time series. The objective of this work is to analyze with DFA cardiovascular alterations that are not present at rest in order to determine the cardiac stress. The RR series of healthy subjects with an average age of 20 years old and subjects with an average age of 40 years old, both with sedentary lifestyle, under stress tests on a treadmill at different speeds were obtained from a Holter monitor. These series are recorded both at rest and at stress test. Information about cardiac stress is acquired from the stress test series. In principle, it is possible to know the health status and physical condition from the subject. The main purpose is to find correlations between the DFA exponent and the stress test parameters. It was verified that RR time series of young people have long-range correlations and these correlations decrease for RR time series of middle-aged adults. In addition, it was able to determine, at least qualitatively, the cardiac stress during the different stress tests which is an important parameter to assess the heart condition. [ABSTRACT FROM AUTHOR]

The paper presents the experimental results on the bending strength of the ceramic composite Al2O3–ZrO2 at three-point bending in a wide temperature range. The ceramic samples sintered at 1650C had porosity of 6.5% with the high temperature dependence of the bending strength. The ceramic samples sintered at 1400C had porosity of 21% with the not significant temperature dependence of the bending strength, which does not exceed 10%. It has been shown that the temperature increasing during test series leads to a decrease in bending strength for all types of ceramic samples. This effect is associated with possible martensitic transformations in the composite and a decreasing of fracture energy. Experiments, which were carried out at a negative temperature, showed abnormal behavior of the composites with the porosity of 6.5% with an increasing of bending strength by 30%. [ABSTRACT FROM AUTHOR]

Experiments were conducted to qualify a multi-diagnostic characterization procedure for the performance output of a detonator when fired into a poly(methyl methacrylate) (PMMA) witness block. A suite of optical diagnostics were utilized in combination to both bound the shock wave interaction state at the detonator/PMMA interface and characterize the nature of the shock wave decay in PMMA. The diagnostics included the Shock Wave Image Framing Technique (SWIFT), a photocathode tube streak camera, and photonic Doppler velocimetry (PDV). High-precision, optically clear witness blocks permitted dynamic flow visualization of the shock wave in PMMA via focused shadowgraphy. SWIFT- and streak-imaging diagnostics captured the spatiotemporally evolving shock wave, providing a two-dimensional temporally discrete image set and a one-dimensional temporally continuous image, respectively. PDV provided the temporal velocity history of the detonator output along the detonator axis. Through combination of the results obtained, a bound was able to be placed on the interface condition and a more-physical profile representing the shock wave decay in PMMA for an explodingbridgewire detonator was achieved. [ABSTRACT FROM AUTHOR]

Within the framework of investigations, an exhaust gas component made of Titanium Grade 2 was produced by means of Hot Metal Gas Forming (HMGF) at the Fraunhofer IWU in Chemnitz, Germany. The semi-finished products were two-fold bent, thermal joined, calibrated and pre-formed tubes. So far, a three-stage internal high-pressure forming process at room temperature plus two necessary intermediate heat treatments were used to produce the component. Due to its complexity as well as the limited forming ability of Titanium Grade 2 at room temperature an one step Hot Metal Gas Forming was developed to replace the former procedure. [ABSTRACT FROM AUTHOR]

Observational data cannot be used for climate research without a clear knowledge about the state of the data in terms of temporal homogeneity. The main steps and results of the homogenization procedure applied to a surface solar radiation dataset over the Italian territory for the period 1959-2013 are discussed. [ABSTRACT FROM AUTHOR]

Investigations on PA6-GF50 integral foams have been carried out using different material systems: longfiberand shortfiber-reinforced PA6 as well as unreinforced PA6 as a reference material. Both chemical and physical blowing agents were applied. Breathing mold technology (decompression of the mold) was selected for the foaming process. The integral foam design, which can be conceived as a sandwich structure, helps to save material in the neutral axis area and maintains a distance between load-bearing, unfoamed skin layers. For all test series an initial mold gap of 2.5 mm was chosen and the same amount of material was injected. In order to realize different density reductions, the mold opening stroke was varied. The experiments showed that, at a constant mass per unit area, integral polyamide 6 foams have a significantly higher bending stiffness than compact components, due to their higher area moment of inertia after foaming. At a constant surface weight the bending stiffness in these experiments could be increased by up to 600%. Both shortfiber- and longfiber-reinforced polyamide 6 showed an increase in energy absorption during foaming. [ABSTRACT FROM AUTHOR]

Linear shaped charges (LSC) are typically manufactured in continuous lengths and formed into an inverted "V". They use explosive force to cut through a target with a straight blade, usually in the demolition industry, but there is also significant interest in cutting a circle with the LSC formation for military and breaching applications. While some curved LSCs do exist, there are limitations for the curve due to the manufacturing process; additionally depth of penetration is reduced as the blade is formed at an angle due to varying inside and outside dimensions of the LSC. The run-up/run-down effect that is prevalent with the use of LSCs also poses as an obstacle towards cutting a full circle, as the optimal penetration depth is not reached in the run-up/run-down areas. Additive manufacturing allows for geometric complexity not possible in other manufacturing techniques. In this work, selective laser melting with a Renishaw 250 system was utilized. Using additive manufacturing, two separate design challenges were addressed; reducing the amount of run-up that occurs, and producing curved penetration with the LSC blade. LSC performance was evaluated by the depth of penetration, reduction of the amount of run-up that occurs, and curvature in the cut compared to traditional liners. The aim of this work is to show the potential for reducing the amount of run-up and curving the blade of a LSC through additive manufacturing of LSC liners. [ABSTRACT FROM AUTHOR]

We have developed optical thermocouples (OTCs) for use in explosive fireballs. The OTC consist of an optical fiber with a fluorescent phosphor coating. The phosphor, Dy-doped YAG, is a well-known two-color thermometry material, which is excited with a pulsed ultraviolet laser. As temperature increases, a higher excited energy level is populated and starts to emit fluorescence. Temperature can be determined by monitoring the intensity ratio of two fluorescence bands. We recently conducted our first field tests of these OTCs and report on their performance as well as further design improvements. [ABSTRACT FROM AUTHOR]

A series of experiments are currently underway at the Detonation Science and Technology group, within Los Alamos National Laboratory, to study the overdriven-detonation states achievable in energetic materials as a result of detonation-wave interactions. A multi-component, energetic-material array was designed to study the amplification of velocity and pressure states produced by spherically diverging detonation waves in pentaerythritol tetranitrate (PETN) output charges. The unique geometry provides a low-jitter, highly controlled series of interactions between three independent-detonation inputs. Streak-camera imaging was performed on the output face of PETN pellets ranging in thickness from 2.5 – 10 mm to characterize the resulting breakout profile. Additionally, photonic Doppler velocimetry (PDV) measurements were collected at the output-pellet surface to determine simultaneity within the system. Detonation-wave velocities upwards of 16 mm/µs were measured, as compared to a steady-state detonation velocity of 7.9 mm/µs for the PETN pressing density investigated. Additional experiments are being conducted to measure the pressure amplification generated at key areas of interaction. [ABSTRACT FROM AUTHOR]

The process of foam injection molding is state of the art for thermoplastic materials, whereas very little research has been carried out applying this technique for thermosetting materials. This publication demonstrates the feasibility of a foam injection molding process with phenolic resin as a thermosetting material. Test series were carried out applying different foaming agents, which differ in their decomposition process. One is exothermic, another one is endothermic and the third creates foam due to thermal expansion. The maximum weight reduction achievable for each foaming agent has been determined by gradually decreasing the shot volume until incomplete filling occurs. The foam structures are analyzed by microsections and evaluated with a digital image processing method. Additionally, the effect on mechanical properties is discussed by evaluating the bending stress. The exothermic foaming agent shows the best foam patterns achieving a maximum weight reduction of approximately 50 %, whereas the endothermic and the thermal foaming agent can reduce the weight by approximately 25 % and 20 % respectively. The bending stress decreases significantly with an increasing proportion of foam in all samples. [ABSTRACT FROM AUTHOR]

Here we present details of an experiment for verifying the liquid helium vessel relief device for the Alpha Magnetic Spectrometer-02 (AMS-02). The relief device utilizes a series of rupture discs designed to open in the event of a vacuum failure of the AMS-02 cryogenic system. A failure of this type is classified to be a catastrophic loss of insulating vacuum accident. This apparatus differs from other approaches due to the size of the test volumes used. The verification apparatus consists of a 250 liter vessel used for the test quantity of liquid helium that is located inside a vacuum insulated vessel. A large diameter valve is suddenly opened to simulate the loss of insulating vacuum in a repeatable manner. Pressure and temperature vs. time data are presented and discussed in the context of the AMS-02 hardware configuration. [ABSTRACT FROM AUTHOR]

A test series was conducted on formulations containing TATB and RDX (PBXN-7), TATB and HMX (PBXW-14) and DAAF and HMX where corner turning and detonation propagation data were measured. Corner turning is a function of temperature and can be used to evaluate the completeness of explosive work. In order to show cold temperature performance behavior, this test was developed to compare the front curvature of these materials at a variety of diameters, explosive compositions, and temperatures. Shots were fired at ambient and -55 °C. The test apparatus developed for this lends itself to streak imaging across the pellet face, and time of arrival scope data from magnet wire embedded between the pellets. The test set up, fixturing and data analysis will be discussed. The results of the shots showed interesting diameter effects on the detonation velocity of the formulations and gave an excellent comparison of the relative curvatures as a function of temperature. [ABSTRACT FROM AUTHOR]

A model and procedure to detect fire location and inverse fire intensity is developed. Markov Chain Monte Carlo sampling based on the Bayesian inference is used to invert the parameters such as source location and its strength. Two test cases are used to evaluate the model. First, the model is validated using experimental data from the “NBS Multi-room Test Series”. Second, a two-story office building fire with 35 compartments is used to investigate the sensitivity and reliability of the model. It is shown that predicted fire source and intensity agree well with the actual value. Then the effects of the sensors’ time sampling interval and intersensor spacing on the sensitivity and reliability of the method are studied respectively. The results indicate that small time sampling interval generally result in high estimation performance, but the decreasing of the intersensor space is not significantly helpful to improve the accuracy of the inverse intensity if the time sampling interval is small enough. In addition, it is discovered that the accuracy of the predicted fire location is not affected by the accuracy of the forward fire model, while the accuracy of predicted fire intensity is sensitive to the systematic errors or the accuracy of the forward model. [ABSTRACT FROM AUTHOR]

Infrared NDE techniques have proven to be superior for imaging of flaws in ceramic matrix composites (CMC) and carbon silicon carbide composites (C/SiC). Not only can one obtain accurate depth gauging of flaws such as delaminations and layered porosity in complex-shaped components such as airfoils and other aeronautical components, but also excellent reproducibility of image data is obtainable using the STTOF (Synthetic Thermal Time-of-Flight) methodology. The imaging of large complex shapes is fast and reliable. This methodology as applied to large C/SiC flight components at the NASA Dryden Flight Research Center will be described. [ABSTRACT FROM AUTHOR]

Evaluation of strength and quality of smell is today still primarily done with human sensory panels. For a range of applications, technical systems for an objective smell assessment would provide a great benefit in R&D and also day-to-day application. The project presented here specifically addresses the problem of assessing the strength and unpleasantness of smell caused by sweat in shoes and socks by an E-nose system. The ultimate goal is to provide a tool for developing improved shoe/sock systems with optimized materials. The main approach to achieve this goal is to find a correlation between the assessment of a human sensory panel and the complex sensor response patterns of an E-Nose system to appraise the smell of sweat in shoes and socks. Therefore a range of test persons wear shoes and socks under defined ambient conditions in a controlled test environment as well as during everyday use. Afterwards the smell of the shoes and socks is both measured with the E-Nose system and assessed by a human sensory panel. We report here the results of the first larger test series and the identified correlation between the E-Nose system and the human assessment of the smell of sweat. [ABSTRACT FROM AUTHOR]

The failure characterization of brittle materials like glass is of fundamental importance in describing the penetration resistance against projectiles. A critical question is whether this failure front remains “steady” after the driving stress is removed. A test series with short gold rods (D = 1 mm, L/D≈5–11) impacting borosilicate glass at ∼1 to 2 km/s was carried out to investigate this question. The reverse ballistic method was used for the experiments, and the impact and penetration process was observed simultaneously with five flash X-rays and a 16-frame high-speed optical camera. Very high measurement accuracy was established to ensure reliable results. Results show that the failure front induced by rod impact and penetration does arrest (ceases to propagate) after the rod is totally eroded inside the glass. The impact of a second rod after a short time delay reinitiates the failure front at about the same speed. [ABSTRACT FROM AUTHOR]

The incidental effects of gaps in detonating explosives have been observed for over two centuries, yet the root cause of peripheral damage due to these features has been a partial mystery. To evaluate such damage for PBX 9501, a test series has been performed that examines single and multiply-directed detonations crossing gaps of varying widths and angles relative to the detonation wave fronts. Damage is evaluated with steel witness plates and quantified through trench profiling and photographic analysis. In addition, streak camera traces are used to track detonations along explosive material surfaces and across gaps. Such traces allow the quantification of timing delays due to the gap reinitiation process. For some reinitiation tests, a second detonation wave is directed to interfere at varying times with the post-gap initiation process of the first wave, thus allowing complex wave-wave interactions to be investigated in detail. With these cumulative observations, further insight into the mechanism of extrinsic damage due to gaps is gained. [ABSTRACT FROM AUTHOR]

Heat pipe life tests described in the literature have seldom been conducted on a systematic basis. Typically one or more heat pipes are built and tested for an extended period at a single temperature with simple condenser loading. The objective of this work was to establish an approach to generate carefully controlled data that can conclusively establish heat pipe operating life with material-fluid combinations capable of extended operation. Approximately 10 years of operational life might be compressed into 3 years of laboratory testing through a combination of increased temperature and mass fluence. To accomplish this goal test series have been identified, based on American Society for Testing and Materials (ASTM) specifications, to investigate long term corrosion rates. The heat pipes selected for demonstration purposes are fabricated from a Molybdenum-44.5%Rhenium refractory metal alloy and include an internal crescent annular wick design formed by hot isostatic pressing. A processing methodology has been devised that incorporates vacuum distillation filling with an integrated purity sampling technique for the sodium working fluid. Energy is supplied by radio frequency induction coils coupled to the heat pipe evaporator with an input range of 1 to 5 kW per unit while a static gas gap coupled water calorimeter provides condenser cooling for heat pipe temperatures ranging from 1123 to 1323 K. The test chamber’s atmosphere would require active purification to maintain low oxygen concentrations at an operating pressure of approximately 75 torr. The test is designed to operate round-the-clock with 6-month non-destructive inspection intervals to identify the onset and level of corrosion. At longer intervals specific heat pipes are destructively evaluated to verify the non-destructive observations. Accomplishments prior to project cancellation included successful demonstration of the heat pipe wick fabrication technique, establishment of all engineering designs, baselined operational test requirements and procurement/assembly of supporting test hardware systems. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Motivated by the need for accurate numerical models when simulating combined rotary stretch bending and local calibration, this paper presents results obtained by using shell element models in LS-DYNA, and by varying: the yield surface, the number of integration points and the die mesh. The study was conducted on thin-walled, extruded double-chambered, hollow aluminium sections, and the numerical findings are supported by full scale experiments. A test series, comprising of profiles with four different wall thicknesses, was completed in rotary stretch bending and in rotary stretch bending with subsequent local calibration. The introduction of local calibration led to a reduction in the magnitude of elastic springback. Improved prediction of the cross sectional deformation was obtained by using the anisotropic Barlat 96 instead of an isotropic yield surface. At increasing complexity — as seen when including local calibration and increased wall thickness — the need for a more accurate representation of the profile features was identified. The results indicate, remembering that rotary stretch bending is a complex forming operations, that the correlation in experimental to numerical findings can be improved by monitoring the experimental specimen more closely. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

The Safe Affordable Fission Engine (SAFE) test series addresses Phase 1 Space Fission Systems issues in particular non-nuclear testing and system integration issues leading to the testing and non-nuclear demonstration of a 400-kW fully integrated flight unit. The first part of the SAFE 30 test series demonstrated operation of the simulated nuclear core and heat pipe system. Experimental data acquired in a number of different test scenarios will validate existing computational models, demonstrated system flexibility (fast start-ups, multiple start-ups/shut downs), simulate predictable failure modes and operating environments. The objective of the second part is to demonstrate an integrated propulsion system consisting of a core, conversion system and a thruster where the system converts thermal heat into jet power. This end-to-end system demonstration sets a precedent for ground testing of nuclear electric propulsion systems. The paper describes the SAFE 30 end-to-end system demonstration and its subsystems. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

The Advanced Shuttle Upper Stage (ASUS) concept addresses safety concerns associated with cryogenic stages by launching empty, and filling on ascent. The ASUS employs a rapid chill and fill concept, where a spray bar is used to completely chill the tank before fill. Thus the vent valve can be closed during the fill process. The first tests of this concept, using a flight size (not flight weight) tank, were conducted at Marshall Space Flight Center (MSFC) during the summer of 2000. The objectives of the testing were to: 1. Demonstrate that a flight size tank could be filled in roughly 5 minutes to accommodate the shuttle ascent window, 2. Demonstrate a no-vent fill of the tank, and 3. Gather data to validate analytical models. A total of fourteen tests were conducted. Models of the test facility fill and vent systems, as well as the tank, were constructed. The objective of achieving tank fill in 5 minutes was met during the test series. However, liquid began to accumulate in the tank before it was chilled. Since the tank was not chilled until the end of each test, vent valve closure during fill was not possible. Even though the chill and fill process did not occur as expected, reasonable model correlation with the test data was achieved. [ABSTRACT FROM AUTHOR]

The use of gamification in education is a continual process for developing the learning abilities of people. It is a trending concept used by corporates for providing a learning environment for the employees, while schools and colleges are also adopting this to foster the students with exciting and exciting learning methods. This teaching approach increases students' motivation and makes the cumbersome process more engaging. Gamification makes use of various design elements in the atmosphere of education. This learning technique is gaining more popularity in today's world (Koivisto &Hamari, 2019). However, there is a mixed element of success associated with its application in the institutional contexts. The following study highlights the importance of gamification in higher education and other aspects, such as the challenges faced while implementing this technique, the added benefits and opportunities that come along, and the solution to different issues arising in this context. The study used a sample of 223 respondents to determine the function of gamification in courses and the influence on students in higher education. The study concludes that gamification can engage, Innovative and productive, learning to new processes, and it also helps retain knowledge. It is also found that gamification has a significant impact on higher education students. [ABSTRACT FROM AUTHOR]

In the course of ever increasing demands on high-performance products, the achievement of a high melt quality is an important factor for the economic operation of an extrusion line. To increase this quality, special shearing and mixing sections are usually used at the screw tip. An important representative of this class is the faceted mixing section, which is characterized by a very good distributive mixing quality effect. Due to its intersecting flow channels and the resulting characteristic rhombs, the geometry is very variable in design. The geometry can be designed to be more or less pressure dropping, whereby a higher pressure consumption is also often accompanied by a higher mixing quality. Therefore, the mixing quality is to be assessed on the basis of CFD simulations and subsequent performance of the so-called particle tracking method to assess the homogeneity of a large number of faceted mixers based on a Central Composite Design (CCD). For this purpose, massless tracer particles are used at the flow inlet and their distribution at the flow outlet is assessed using a novel method based on Delaunay triangulation. In combination with previous investigations on the pressure-throughput behavior, the conflict between these two target goals will then be discussed on the basis of numerical optimization. The aim is to develop a balanced faceted mixer with a good mixing quality and a favorable pressure-throughput behavior. [ABSTRACT FROM AUTHOR]

Façade claddings with open joints are commonly used in large buildings in Norway. Plane façade panels of fibre cement and high-pressure laminate boards are usually fabricated using joint width of 5 – 10 mm, while solar panel claddings may have joints up to 20 mm. Vertical joints are relatively raintight because the boards are mounted to vertical battens with rubber gaskets placed in between. In contrast, horizontal joints are typically mounted with open joints. The building guidelines recommend that horizontal joints should be protected by small metal profiles to provide rain protection in Norwegian climate. This is unpopular amongst architects as it affects the aesthetics of the horizontal profiles. This study aims to determine the rain resistance of typical open-joint façade claddings, particularly for horizontal joints. The rain testing was performed according to NS-EN 1027:2016 on six different claddings with different horizontal joint openings of 3, 5, and 8 mm. In addition, three horizontal profiles used for protection were tested. Twenty-five different tests were performed. The rain testing demonstrated that the penetration of water through the joint increased with an increase in the joint width. In the case of open horizontal joints, it is impossible to prevent the seepage of water through the joints. The experimental investigation conducted on metal profiles exhibited peculiar results. Two of the three profiles resulted in an increased water seepage behind the panel cladding than that of the open horizontal joints. This was due to the geometric design of the joint profile and the inability to achieve an effective compression between the facade panel and profile. An innovative profile design and supplementary rain testing are required to develop aesthetically acceptable rain tight profiles for open-joint façade claddings. [ABSTRACT FROM AUTHOR]

This paper addresses the requirements for components in solar thermal power plants using molten salt as heat transfer fluid. For both line-focused and tower systems, operation requirements for various components are compiled from standards, publications, and operating experience. This also includes information on the typical sizes of the components. Based on the collated operating parameters, tests were carried out with valves and flange connections, provided by industrial partners, in the TESIS:com test facility. Shutoff valves without valve spindle heaters and bellows were tested primarily through continuous open/close cycles at temperatures between 290 and 560 °C. The tests were conducted in two different campaigns in which the valves were exposed to Solar Salt for 4.5 and 8 days, respectively. After the first test campaign, the knowledge obtained was used to develop an improved valve packing. In addition, a new development of flange connections was subjected to high temperature gradients (shocks) and freezing. [ABSTRACT FROM AUTHOR]

The plastic-bonded explosive (PBX) 9502 is a viscoelastic, high-solids loaded polymer bound composite comprised of 95 weight% (wt%) TATB explosive crystals and 5 wt% FK-800 polymer binder. The uniaxial quasi-static mechanical properties have been studied and characterized extensively over 25+ years, including creep. Creep is the strain evolution over time as a result of an asymmetric load typically at temperatures above ambient. Creep measurements to failure can take excessively long periods of time depending on various factors including applied stress, temperature, and loading rate that render a single test to failure impossible. Using the principles of time-temperature-stress superposition (TTSSP), short-term creep tests at various applied stresses and temperatures can be used for long-term creep predictions. The TTSSP model shifts short-term test data using two factors, one for temperature and stress, creating a master curve at a reference test condition. The master curve can be shifted to predict the creep response at any desired test condition. PBX 9502 compression specimens were tested at three temperatures and various applied stresses. This work discusses the TTSSP analysis of PBX 9502 compressive creep data to create a single comprehensive master curve. [ABSTRACT FROM AUTHOR]