Journal articles on the topic 'Space mechanism in-flight testing'
To see the other types of publications on this topic, follow the link: Space mechanism in-flight testing.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Space mechanism in-flight testing.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Taylor, Gerald R., and Robert P. Janney. "In vivo testing confirms a blunting of the human cell-mediated immune mechanism during space flight." Journal of Leukocyte Biology 51, no. 2 (February 1992): 129–32. http://dx.doi.org/10.1002/jlb.51.2.129.
Full text
2
Huber, F. W., P. D. Johnson, O. P. Sharma, J. B. Staubach, and S. W. Gaddis. "Performance Improvement Through Indexing of Turbine Airfoils: Part 1—Experimental Investigation." Journal of Turbomachinery 118, no. 4 (October 1, 1996): 630–35. http://dx.doi.org/10.1115/1.2840918.
Full textAbstract:
This paper describes the results of a study to determine the performance improvements achievable by circumferentially indexing successive rows of turbine stator airfoils. An experimental/analytical investigation has been completed that indicates significant stage efficiency increases can be attained through application of this airfoil clocking concept. A series of tests was conducted at the National Aeronautics and Space Administration’s (NASA) Marshall Space Flight Center (MSFC) to experimentally investigate stator wake clocking effects on the performance of the Space Shuttle Main Engine Alternate Fuel Turbopump Turbine Test Article. Extensive time-accurate Computational Fluid Dynamics (CFD) simulations have been completed for the test configurations. The CFD results provide insight into the performance improvement mechanism. Part one of this paper describes details of the test facility, rig geometry, instrumentation, and aerodynamic operating parameters. Results of turbine testing at the aerodynamic design point are presented for six circumferential positions of the first stage stator, along with a description of the initial CFD analyses performed for the test article. It should be noted that first vane positions 1 and 6 produced identical first to second vane indexing. Results obtained from off-design testing of the “best” and “worst” stator clocking positions, and testing over a range of Reynolds numbers are also presented. Part two of this paper describes the numerical simulations performed in support of the experimental test program described in part one. Time-accurate Navier–Stokes flow analyses have been completed for the five different turbine stator positions tested. Details of the computational procedure and results are presented. Analysis results include predictions of instantaneous and time-average midspan airfoil and turbine performance, as well as gas conditions throughout the flow field. An initial understanding of the turbine performance improvement mechanism is described.
3
Z˙bikowski, Rafał, Cezary Galin´ski, and Christopher B. Pedersen. "Four-Bar Linkage Mechanism for Insectlike Flapping Wings in Hover: Concept and an Outline of Its Realization." Journal of Mechanical Design 127, no. 4 (June 27, 2005): 817–24. http://dx.doi.org/10.1115/1.1829091.
Full textAbstract:
This paper describes the concept of a four-bar linkage mechanism for flapping wing micro air vehicles and outlines its design, implementation, and testing. Micro air vehicles (MAVs) are defined as flying vehicles ca. 150 mm in size (handheld), weighing 50–100 g, and are developed to reconnoiter in confined spaces (inside buildings, tunnels, etc.). For this application, insectlike flapping wings are an attractive solution and, hence, the need to realize the functionality of insect flight by engineering means. Insects fly by oscillating (plunging) and rotating (pitching) their wings through large angles, while sweeping them forward and backward. During this motion, the wing tip approximately traces a figure eight and the wing changes the angle of attack (pitching) significantly. The aim of the work described here was to design and build an insectlike flapping mechanism on a 150 mm scale. The main purpose was not only to construct a test bed for aeromechanical research on hover in this mode of flight, but also to provide a precursor design for a future flapping-wing MAV. The mechanical realization was to be based on a four-bar linkage combined with a spatial articulation. Two instances of idealized figure eights were considered: (i) Bernoulli’s lemniscate and (ii) Watt’s sextic. The former was found theoretically attractive, but impractical, while the latter was both theoretically and practically feasible. This led to a combination of Watt’s straight-line mechanism with a drive train utilizing a Geneva wheel and a spatial articulation. The actual design, implementation, and testing of this concept are briefly described at the end of the paper.
4
Merriam, E. G., J. E. Jones, S. P. Magleby, and L. L. Howell. "Monolithic 2 DOF fully compliant space pointing mechanism." Mechanical Sciences 4, no. 2 (December 2, 2013): 381–90. http://dx.doi.org/10.5194/ms-4-381-2013.
Full textAbstract:
Abstract. This paper describes the conception, modeling, and development of a fully compliant two-degree-of-freedom pointing mechanism for application in spacecraft thruster, antenna, or solar array systems. The design objectives and the advantages of a compliant solution are briefly discussed. Detailed design decisions to meet project objectives are described. Analytical and numerical models are developed and subsequently verified by prototype testing and measurements in several iterations. A final design of the 3-D printed titanium monolithic pointing mechanism is described in detail and its performance is measured.
5
ZHAO Hai-bo, 赵海波, 赵伟国 ZHAO Wei-guo, 董吉洪 DONG Ji-hong, 杨维帆 YANG Wei-fan, 刘奉昌 LIU Feng-chang, 周平伟 ZHOU Ping-wei, and 姜. 萍. JIANG Ping. "Accuracy analysis and testing for secondary mirror adjusting mechanism in large space telescope." Optics and Precision Engineering 27, no. 11 (2019): 2374–83. http://dx.doi.org/10.3788/ope.20192711.2374.
Full text
6
Michaels, Dan, and Alon Gany. "Modeling and testing of a tube-in-tube separation mechanism of bodies in space." Acta Astronautica 129 (December 2016): 214–22. http://dx.doi.org/10.1016/j.actaastro.2016.09.013.
Full text
7
Wang, Junwei, Lei Zhang, Guohua Li, Ran Liu, Juan Ning, Xiao Han, and Xin He. "Research and Verification of Key Techniques in the Simulation of Space Extremely Rapid Decompression in Millisecond." International Journal of Aerospace Engineering 2021 (April 5, 2021): 1–11. http://dx.doi.org/10.1155/2021/6634468.
Full textAbstract:
The research of rapid decompression with its effect assessment and protection technology is the problem that must be faced by the future exploration projects such as near space exploration, deep space exploration, and long-term lunar or Mars base. A new reusable quick opening mechanism which can be opened in millisecond is designed to meet the testing requirement of ground simulator for extremely rapid decompression, and the testing results show that the quick opening mechanism can be opened within 0.1 s. The mathematical formulation is also developed, and the comparisons with the results from the literature demonstrate its validity. The CFD simulation and the verification system are established for the airflow in the rapid decompression process under different opening degrees. The simulation results show that the effect of the opening on the decompression process is very obvious and the decompression time corresponding to 50%, 75%, and 100% opening is 479.1 ms, 320.7 ms, and 290.1 ms, respectively. The testing results also show a consistent trend which is 583 ms, 450 ms, and 384 ms, respectively, to reach the equilibrium state.
8
Hymer, W. C., R. E. Grindeland, T. Salada, P. Nye, E. J. Grossman, and P. K. Lane. "Experimental modification of rat pituitary growth hormone cell function during and after spaceflight." Journal of Applied Physiology 80, no. 3 (March 1, 1996): 955–70. http://dx.doi.org/10.1152/jappl.1996.80.3.955.
Full textAbstract:
Space-flown rats show a number of flight-induced changes in the structure and function of pituitary growth hormone (GH) cells after in vitro postflight testing (W. C. Hymen, R. E. Grindeland, I. Krasnov, I, Victorov, K. Motter, P. Mukherjee, K. Shellenberger, and M. Vasques. J. Appl. Physiol. 73, Suppl.: 151S-157S, 1992). To evaluate the possible effects of microgravity on growth hormone (GH) cells themselves, freshly dispersed rat anterior pituitary gland cells were seeded into vials containing serum +/- microM hydrocortisone (HC) before flight. Five different cell preparations were used: the entire mixed-cell population of various hormone-producing cell types, cells of density < 1.071 g/cm3 (band 1), cells of density > 1.071 g/cm3 (band 2), and cells prepared from either the dorsal or ventral part of the gland. Relative to ground control samples, bioactive GH released from dense cells during flight was reduced in HC-free medium but was increased in HC-containing medium. Band 1 and mixed cells usually showed opposite HC-dependent responses. Release of bioactive GH from ventral flight cells was lower; postflight responses to GH-releasing hormone challenge were reduced, and the cytoplasmic area occupied by GH in the dense cells was greater. Collectively, the data show that the chemistry and cellular makeup of the culture system modifies the response of GH cells to microgravity. As such, these cells offer a system to identify gravisensing mechanisms in secretory cells in future microgravity research.
9
Konovalov, A. M., and V. I. Kugushev. "Mechanism of excitatioon of natural vibrations of fireclay products and its application in flaw detection." NOVYE OGNEUPORY (NEW REFRACTORIES), no. 10 (November 25, 2022): 55–62. http://dx.doi.org/10.17073/1683-4518-2022-10-55-62.
Full textAbstract:
In this article, using the example of developing a technique for non-destructive testing of a fireclay product («asterisks») using the natural vibrations of the object of control, a mathematical model is presented that allows us to specifically describe the process of converting an external dynamic effect into the natural vibrations of the part. The peculiarity of the model is that, firstly, it is a carrier of the free energy of elastic deformation and the process of natural oscillations is formed in it. Secondly, the model is a Riemannian space in which all dynamic parameters are constant and reduced to zero, i.e. the model does not exist physically, but only as a functional space. The proposed model can serve as an effective tool for analyzing the processes observed during non-destructive testing and vibration diagnostics. Ill. 7. Ref. 22.
10
Zhou, Hongming, Peiyuan Li, Longfei Wu, and Qiankun Gao. "A wavelet analysis-based matching pursuit algorithm for an accurate ultrasonic TOFD measurement." Insight - Non-Destructive Testing and Condition Monitoring 62, no. 11 (November 1, 2020): 662–68. http://dx.doi.org/10.1784/insi.2020.62.11.662.
Full textAbstract:
The time-of-flight diffraction (TOFD) technique is used as an important non-destructive testing method in weld integrity evaluation and failure analysis. However, an accurate measurement of the time-of-flight (TOF) has proven to be difficult due to the low time resolution of the measured signal. Conventional deconvolution techniques have been used to improve the time resolution of the signal but are not effective for ultrasonic TOFD signals because the frequency contents of the signals are non-static in space-frequency distribution. To overcome this problem, a method is proposed in this paper that estimates the TOF in two steps. In the first step, the measured signal is decomposed into a series of narrowband signals using a wavelet transform and an atom dictionary is adaptively established according to the characteristics of a selected narrowband signal. In the second step, matching pursuit (MP) is used to derive a sparse representation of the selected narrowband signal. A steel specimen with artificial defects is prepared, experiments are carried out and the results confirm the efficacy of the proposed algorithm.
11
Phillips, W. M., and J. W. Stearns. "Alkali Metal/Halide Thermal Energy Storage Systems Performance Evaluation." Journal of Solar Energy Engineering 109, no. 3 (August 1, 1987): 235–37. http://dx.doi.org/10.1115/1.3268212.
Full textAbstract:
Materials compatibility and durability of advanced salt/alkali metal slurry thermal energy storage systems has been demonstrated [1]. Applications are being evaluated for both space and terrestrial solar thermal power conversion [2]. High energy density of these thermal storage systems is achieved by colocation of heat input and extraction within the slurry mixture which is overwhelmingly phase-change salt. This paper addresses performance testing of these systems. Understanding of mechanisms of both micro and macro stratification of the slurry is necessary to fully predict system performance as a function of gravity and system geometry. If it can be shown the gravity stratification effects are secondary to a combination of: (1) liquid metal film adhesion (wetting) to the heat exchange surfaces and solidified salt particles, (2) solubility of alkali metal in the salt-rich phase, and (3) stirring produced by liquid to vapor conversion of the alkali metal, then system geometry limitations are greatly relaxed for space application. Performance testing was accomplished using a sodium heat pipe to transfer heat from the slurry canister to a gas gap calorimeter. Testing was accomplished with the heat pipe installed only in the vapor space above the alkali metal/salt slurry and with an increase heat pipe and minimum vapor space. This testing conclusively demonstrated the effectiveness of the pseudo-heat-pipe type heat transfer mechanism operating in the slurry system under terrestrial conditions.
12
Fauzia, Marliana Eka. "Mengembalikan Tahapan Uji Publik Pada Pilkada." Jurnal Adhyasta Pemilu 3, no. 2 (December 6, 2021): 121–40. http://dx.doi.org/10.55108/jap.v3i2.14.
Full textAbstract:
The writing of this article is intended to evaluate the urgency of revising the Pilkada Law, on eliminating public examination points. The DPR removed public test points in the revision of the Election Law No. 1 of 2015, and was replaced by the Election Law No. 8 of 2015. Until the current election law No. 10 of 2016 there has been no re-discussion regarding the stages of public testing. The public test is a stage of competency and integrity testing for candidates for regional head and representative in an open manner which is independently formed by the Provincial / Regency / City KPU. Public test points were removed on the grounds that they were inefficient and time consuming. Based on this, the authors identify that the elimination of public testing can limit public participation in deliberative public spaces. And if the public test is returned at the election stage, it can improve the quality of democracy. As a theoretical review in this article the writer uses the concept of public space. While the research method uses qualitative through literature study. The results of this paper indicate that it is important to maintain a public test mechanism to restore the public space for the implementation of the elections. The existence of this public space ensures that there is space for public participation, the public can find out the track record of the candidates, build communication between candidates and voters and that public trials can be used as a deliberative campaign. Therefore, the public test can be returned to the election mechanism by adding a committee from various elements of society (farmers, laborers, entrepreneurs, village heads, educators, students and other elements of civil society). So that the public test becomes the preliminary election before the election day takes place.
13
Berlin, M., N. Goossens, H. W. Oelze, and C. Braxmaier. "Launch lock system for reaction wheels." CEAS Space Journal 13, no. 4 (February 18, 2021): 583–89. http://dx.doi.org/10.1007/s12567-021-00353-9.
Full textAbstract:
AbstractLaunch loads are critical forces to the payload. Many structures are not designed to survive these loads, thus, additional systems which absorb them are required. These launch lock mechanisms are available in different varieties. For a future magnetic bearing reaction wheel, two different principles of launch lock mechanism concepts were developed and tested. The first one is based on a spring mechanism, while the second uses electromagnetism to move the locking pins. A first testing with prototypes of both was conducted to evaluate the functionality. Subsequently improvements regarding reducing the mass and construction volume were incorporated in the design. In the course of this, additive manufacturing with PLA filament has been used to study possible applications for these mechanisms. The spring concept resulted to be more reliable than the electromagnetic one, but requires a damping mechanism. A usage of additive manufactured PLA components is a promising possibility for the production.
14
Dündar-Coecke, Selma, Gideon Goldin, and Steven A. Sloman. "Causal reasoning without mechanism." PLOS ONE 17, no. 5 (May 13, 2022): e0268219. http://dx.doi.org/10.1371/journal.pone.0268219.
Full textAbstract:
Unobservable mechanisms that tie causes to their effects generate observable events. How can one make inferences about hidden causal structures? This paper introduces the domain-matching heuristic to explain how humans perform causal reasoning when lacking mechanistic knowledge. We posit that people reduce the otherwise vast space of possible causal relations by focusing only on the likeliest ones. When thinking about a cause, people tend to think about possible effects that participate in the same domain, and vice versa. To explore the specific domains that people use, we asked people to cluster artifacts. The analyses revealed three commonly employed mechanism domains: the mechanical, chemical, and electromagnetic. Using these domains, we tested the domain-matching heuristic by testing adults’ and children’s causal attribution, prediction, judgment, and subjective understanding. We found that people’s responses conform with domain-matching. These results provide evidence for a heuristic that explains how people engage in causal reasoning without directly appealing to mechanistic or probabilistic knowledge.
15
Konovalov, A. M., and V. I. Kugushev. "MODEL OF MECHANISM OF CONVERSION OF EXTERNAL ACTION INTO NATURAL OSCILLATIONS." Kontrol'. Diagnostika, no. 281 (November 2021): 10–20. http://dx.doi.org/10.14489/td.2021.11.pp.010-020.
Full textAbstract:
The work presents a geometrical interpretation of a mathematical model intended to give a specific description of the process of conversion of external dynamic action into natural oscillations of a part. Besides geometrical constructions, the essence of the model stems from the strict logic as well, following which the model does not have a tangible embodiment. Nonetheless, it is a function space, in which the process is being generated and energy of natural oscillations is getting accumulated, i.e. the model is an non-material carrier of free energy of elastic oscillations. Material carrier is the very part. The model is represented as the Riemannian space, in which all dynamic parameters are constant and set to zero, therefore, on the one side, it appears as if it does not have any tangible embodiment. On the other side, by nature, the model is a necessary expansion of the function space, which, on the qualitative level, allows to obtain explanation of a number of processes, which are observed experimentally, but to this day were not provided with a specific substantiation from a physics perspective. The proposed model can be an effective tool for analysis of processes, occurring in the course of non-destructive testing and vibration-based diagnostics. For example, the Article presents a theoretical justification of the process of modelling of cracks in the non-destructive testing methods, using natural oscillations of the item being checked. On top of that, it gives a derivation of the formula determining amount of the crack detected through these methods.
16
Du, Mei, Shuang-Xi Yi, Tong Liu, Cui-Ying Song, and Wei Xie. "Testing Blandford–Znajek Mechanism in Black Hole Hyperaccretion Flows for Long-duration Gamma-Ray Bursts." Astrophysical Journal 908, no. 2 (February 1, 2021): 242. http://dx.doi.org/10.3847/1538-4357/abd6bd.
Full text
17
Kiener, Lionel, Hervé Saudan, Florent Cosandier, Gérald Perruchoud, and Peter Spanoudakis. "Innovative concept of compliant mechanisms made by additive manufacturing." MATEC Web of Conferences 304 (2019): 07002. http://dx.doi.org/10.1051/matecconf/201930407002.
Full textAbstract:
The complete redesign for Additive Manufacturing of compliant mechanism structures enables CSEM to develop innovative concepts to drastically reduce the need of machining and assembly after additive manufacturing. Support structures under flexure blades are thus minimised and the overall process becomes more streamlined. Moreover, this concept allows us to easily design and produce monolithic cross flexure pivots with interlocked flexible blades. Based on this concept, CSEM is now developing new architectures of Compliant Mechanisms based on Additive Manufacturing (COMAM) for the European Space Agency (ESA) in the frame of a GSTP research project. The past and current work of design, 3D printing and testing on several compliant mechanisms are presented. These demonstrators will be used as use-case for future high-precision and harsh environment applications such as cryogenic and space.
18
Sánchez, Jonatan, Antonio da Silva, Pablo Parra, Óscar R. Polo, Agustín Martínez Hellín, and Sebastián Sánchez. "ARINC653 Channel Robustness Verification Using LeonViP-MC, a LEON4 Multicore Virtual Platform." Electronics 10, no. 10 (May 15, 2021): 1179. http://dx.doi.org/10.3390/electronics10101179.
Full textAbstract:
Multicore hardware platforms are being incorporated into spacecraft on-board systems to achieve faster and more efficient data processing. However, such systems lead to increased complexity in software development and represent a considerable challenge, especially concerning the runtime verification of fault-tolerance requirements. To address the ever-challenging verification of this kind of requirement, we introduce a LEON4 multicore virtual platform called LeonViP-MC. LeonViP-MC is an evolution of a previous development called Leon2ViP, carried out by the Space Research Group of the University of Alcalá (SRG-UAH), which has been successfully used in the development and testing of the flight software of the instrument control unit (ICU) of the energetic particle detector (EPD) on board the Solar Orbiter. This paper describes the LeonViP-MC architectural design decisions oriented towards fault-injection campaigns to verify software fault-tolerance mechanisms. To validate the simulator, we developed an ARINC653 communications channel that incorporates fault-tolerance mechanisms and is currently being used to develop a hypervisor level for the GR740 platform.
19
Arcodia, R., A. Merloni, K. Nandra, and G. Ponti. "Testing the disk-corona interplay in radiatively-efficient broad-line AGN." Astronomy & Astrophysics 628 (August 2019): A135. http://dx.doi.org/10.1051/0004-6361/201935874.
Full textAbstract:
The correlation observed between monochromatic X-ray and UV luminosities in radiatively-efficient active galactic nuclei (AGN) lacks a clear theoretical explanation despite being used for many applications. Such a correlation, with its small intrinsic scatter and its slope that is smaller than unity in log space, represents the compelling evidence that a mechanism regulating the energetic interaction between the accretion disk and the X-ray corona must be in place. This ensures that going from fainter to brighter sources the coronal emission increases less than the disk emission. We discuss here a self-consistently coupled disk-corona model that can identify this regulating mechanism in terms of modified viscosity prescriptions in the accretion disk. The model predicts a lower fraction of accretion power dissipated in the corona for higher accretion states. We then present a quantitative observational test of the model using a reference sample of broad-line AGN and modeling the disk-corona emission for each source in the LX − LUV plane. We used the slope, normalization, and scatter of the observed relation to constrain the parameters of the theoretical model. For non-spinning black holes and static coronae, we find that the accretion prescriptions that match the observed slope of the LX − LUV relation produce X-rays that are too weak with respect to the normalization of the observed relation. Instead, considering moderately-outflowing Comptonizing coronae and/or a more realistic high-spinning black hole population significantly relax the tension between the strength of the observed and modeled X-ray emission, while also predicting very low intrinsic scatter in the LX − LUV relation. In particular, this latter scenario traces a known selection effect of flux-limited samples that preferentially select high-spinning, hence brighter, sources.
20
Irwan, Y. M., A. R. Amelia, M. Irwanto, W. Z. Leow, Z. Syafiqah, and I. Safwati. "Influences of Hybrid Cooling Mechanism through PV System under Solar Simulator Testing." International Journal of Advances in Applied Sciences 6, no. 3 (September 1, 2017): 213. http://dx.doi.org/10.11591/ijaas.v6.i3.pp213-220.
Full textAbstract:
An increasing efficiency of the solar system can be improved by using hybrid cooling mechanism. This paper presents the impact of hybrid cooling mechanism on PV panel under indoor testing with varying solar intensity. Thus, the fabrication of a solar simulator for indoor testing reacts as the space solar radiation is described. The performance of PV panel which attached to a hybrid cooling mechanism compared with PV panel without cooling mechanism under variation of average solar radiation. Experimental tests were carried out for various average solar radiations by varying the number of lamps and/or the lamp-to-area distance. Without altering the spectral distribution, the characteristic of current-voltage of PV panel was analysed under average solar radiation which varied from 202 W/m<sup>2</sup> to 1003 W/m<sup>2</sup>. As the result, the PV panel with hybrid cooling system explored to generate more power output with decreasing in PV panel temperature. About 15.79 % increment of power output generated by PV panel with cooling at maximum average solar radiation. Furthermore, the PV panel temperature also can be decreased about 10.28 % respectively. The combination of DC fan and water pump as cooling mechanism plays an important role in generating efficient power output from PV panel.
21
Li, Dong, Shulin Liu, Furong Gao, and Xin Sun. "Continual learning classification method for time-varying data space based on artificial immune system." Journal of Intelligent & Fuzzy Systems 40, no. 5 (April 22, 2021): 8741–54. http://dx.doi.org/10.3233/jifs-200044.
Full textAbstract:
Classification methods play an important role in many fields. However, they cannot effectively classify the samples from sample spaces that are varying with time, for they lack continual learning ability. A continual learning classification method for time-varying data space based on artificial immune system, CLCMTVD, is proposed. It is inspired by the intelligent mechanism that memory cells of the biological immune system can recognize and eliminate previous invaders when they attack again very fast and more efficiently, and these memory cells can evolve with the evolution of previous invaders. Memory cells were continuously updated by learning testing data during the testing stage, thus realize the self-improvement of classification performance. CLCMTVD changes a linearly inseparable spatial problem into many classification problems of several different times, and it degenerates into a common supervised learning classification method when all data independent of time. To assess the performance and possible advantages of CLCMTVD, the experiments on well-known datasets from UCI repository, synthetic data and XJTU-SY rolling element bearing accelerated life test datasets were performed. Results show that CLCMTVD has better classification performance for time-invariant data, and outperforms the other methods for time-varying data space.
22
Hung, Chih Ching, Chi Chang Hsieh, Yan Huei Li, and Chyun Chau Lin. "LED Color Mixing Mechanism Design." Applied Mechanics and Materials 284-287 (January 2013): 2894–98. http://dx.doi.org/10.4028/www.scientific.net/amm.284-287.2894.
Full textAbstract:
LED is the solid-state light source of the 21st century that ranges from white light to any color in the entire spectrum. LED lights create static or dynamic illumination in indoor lighting applications. Modern indoor lighting fixtures not only provide illumination, but also are the primary elements that create the atmosphere. The use of gradual mixing of lights or different colors not only makes lights fit more people’s physical and psychological needs, but also improve one’s aesthetic perspectives. However, the LED color mixing technique based on RGB colors requires the package of the RGB chips in on single space for the creation of color mixing through the control of voltage and current. An innovative color mixing technique was proposed in this study. A linkage mechanism was introduced. The individual RGB chips were installed in 3 sets of four-bar linkages to enable color mixing by driving the RGB chips with the crank of the mechanism. The color mixing effects provide a continuing change of colors to meet people’s requirements for color mixing fixtures in certain scenarios. The fixtures incorporating this design can be used for stage lighting and biomedical engineering testing.
23
., Tin Thein Thwel, and G. R. Sinha . "Efficient Data Deduplication Mechanism for Genomic Data." CSVTU International Journal of Biotechnology Bioinformatics and Biomedical 4, no. 2 (September 3, 2019): 52–58. http://dx.doi.org/10.30732/ijbbb.20190402004.
Full textAbstract:
During the data science age, many people tend to access health concerned information and diagnosis using information technology, including telemedicine. Therefore, many researchers attempting to work with medical experts as well as bioinformatics area. In the bioinformatics field, handling the genomic data of human beings becomes essential such as collecting, storing and processing. Genomic data refers to the genome and DNA data of an organism. Unavoidably, genomic data require huge amount of storage for the customized software to analyze. Recently, genome researchers are rising the alarms over big data.This research papers attempts in significant amount of reduction of data storage by applying data deduplication process in genomic data set. Data deduplication, ‘dedupe’ in short can reduce the amount of storage because of its single instance storage nature.Therefore, data deduplication becomes one of the solutions for optimizing the huge amount of storage spaces for genome storage.We have implemented data deduplication method and applied it to genomic data and the deduplication performed successfully by using secure hash algorithm, B++ tree and sub-file level chunking algorithm. The methods were implemented in integrated approach. The files are separated into different chunks with the help of Two Threshold Two Divisors algorithm and hash function is used to get chunk identifiers. Indexing keys are constructed using the identifiersin B+ tree like index structure.Thissystem can reduce the storage space significantly when there exist duplicated data. The preliminary testing is made using NCBI datasets
24
Graham, Sean S., Wangyuan Zong, Jun Feng, and Shengping Tang. "Design and Testing of a Kiwifruit Harvester End-Effector." Transactions of the ASABE 61, no. 1 (2018): 45–51. http://dx.doi.org/10.13031/trans.12361.
Full textAbstract:
Abstract. Mechanisms to aid fruit harvesting are undergoing constant development with increasing available technologies. However, fruits grown on vines, such as kiwifruit, have complex tree architectures and present difficulties in confirming design parameters. The objective of this research was to develop an end-effector for a kiwifruit harvester based on integrating the physical characteristics of the fruit, such as stem length, the space between mature fruits, and the growing environment provided by a trellised system into the design. These properties contribute to developing a mechanism that is lightweight, battery operated, and requires only one translational joint for positioning. Scissor cutting actuated by a linear solenoid is used to provide the required torque of 1.38 Nm to completely sever Hayward variety kiwifruit at the stem using a curved blade with a 20° relief angle. The cutting of the stem is actuated by a force sensor located on the device that enables cutting at less than 10 N, preventing premature detachment of the fruit and damage to the vine. The cutting time was measured to be 0.1 s ±0.03 s per cut. This end-effector design adds to the body of research aimed at developing a fully mechanized kiwifruit harvester. Keywords: Detachment force, End-effector, Fruit harvester, Kiwifruit, Linear solenoid.
25
Zhao, Guohua, Dan Wang, Liangbao Liu, Rui Fanand, and Rukun Mi. "Research on multidimensional loading device of material mechanical test." MATEC Web of Conferences 207 (2018): 03012. http://dx.doi.org/10.1051/matecconf/201820703012.
Full textAbstract:
A multidimensional loading device for the material mechanical test based on Stewart Platform was proposed and manufactured in this paper. A determination method of mechanism parameters toward specific engineering requirements was analysed via inverse kinematics and contact interference boundary condition of mechanism components. A set of optimized mechanism parameters was achieved and then the pose space was obtained. Meanwhile, five repeated quasi-static standard tensile tests were performed on the multidimensional loading device and the standard tensile testing machine, respectively. The average yield strength and ultimate strength of the specimen achieved from the different testers were both merely 1.13%. Results indicated that material mechanical multidimensional loading could be conducted by the parallel mechanism.
26
Sartori, Igor, Synne Lien, Marius Bagle, Harald Walnum, and Benjamin Manrique. "Development and testing of load flexibility KPIs in the ZEN definition." E3S Web of Conferences 362 (2022): 13004. http://dx.doi.org/10.1051/e3sconf/202236213004.
Full textAbstract:
This paper discusses the flexibility KPIs proposed in the context of the Zero Emission Neighborhood (ZEN) definition for characterizing how a building or neighborhood exchanges energy with the surrounding energy system and presents preliminary results of testing them on single, archetype buildings. The KPIs are calculated as the deviation of a flexible load from a baseline, typical load. The results depend on the flexibility sources activated, as well as the flexibility drivers and flexibility goals deployed for the activation. It is shown how the mechanism of flexibility works and how the KPIs can be graphically represented, with emphasis on space heating. Numeric values of the KPIs are given in ranges, given their intrinsic case to case variability and the limited experience so far accumulated with testing them. This stated, it is shown that activating flexibility can bring reductions in ΔCost (in the range of 0% to 20%), in ΔEnergy Stress and ΔPeak power (in the range 20% to 50%) even if this is accompanied by a modest increase in ΔEnergy (in the range 0% to +5%) due to some energy losses.
27
Tufan, Ö., K. Arroyo Ohori, C. León-Sánchez, G. Agugiaro, and J. Stoter. "DEVELOPMENT AND TESTING OF THE CITYJSON ENERGY EXTENSION FOR SPACE HEATING DEMAND CALCULATION." International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLVIII-4/W4-2022 (October 14, 2022): 169–76. http://dx.doi.org/10.5194/isprs-archives-xlviii-4-w4-2022-169-2022.
Full textAbstract:
Abstract. 3D city models are frequently used to acquire and store energy-related information of buildings for energy applications. In this context, CityGML is the most common data model, and the Energy ADE, one of its most complex extensions, provides a systematic way of storing detailed energy-related data in XML format. Contrarily, even though CityGML’s JSON-based encoding, CityJSON, has an extension mechanism, an energy-related CityJSON Extension is missing. This paper, therefore, presents the first results of the development of a CityJSON Energy Extension and space heating demand calculation is utilized as the use case. The simplified version of the Energy ADE, called the Energy ADE KIT profile, is used to create a semi-direct translation to the CityJSON Energy Extension. This Extension is then validated through the official validator of CityJSON and the use case, and improvements are made considering the validation results. The space heating demand is calculated according to the Dutch standard NTA 8800 for a subset of Rijssen-Holten in the Netherlands although the solar gains calculation requires further review. The results show that the final CityJSON Energy Extension provides full support for space heating demand calculations based on the NTA 8800 and eliminates the deep hierarchical structure of the Energy ADE. A comparison on CityJSON file sizes shows a 25.2 MB increase after the required input data is stored in a CityJSON + Energy Extension file, which is not significant considering the high amount of data stored in the file. Overall, this paper shows that the CityJSON Energy Extension could provide an easy-to-use alternative to the CityGML Energy ADE.
28
Chakravarti, Arpita, K. Gowthamarajan, and Jayakumar Venkatesan. "A brief introduction to the universe of space medication." Journal of medical pharmaceutical and allied sciences 11, no. 2 (March 30, 2022): 4770–76. http://dx.doi.org/10.55522/jmpas.v11i2.2946.
Full textAbstract:
In the present era, scientific explorations have crossed the boundaries of our planet and are ready to venture into the unknown in an estimated time span of next 20 years. In the near future, manned missions to space will be for a longer period of time meaning that the human body will be exposed to a foreign environment for a longer duration of time. The space environment has various effects on the human body and if it’s not taken care of; may lead to long-term and irreversible damage. This article outlines some of the novel formulations which could be used for space travel and their stability testing mechanism. Future research should focus on potential advances to ensure that our space programs are well-equipped to assure astronaut safety as they explore deep space objectives. Keywords: Space medicine, Nanotechnology, Drug delivery system, Gold nano, Bionano scaffolds.
29
Ponkin, I. V. "Public Administration and Regulatory Space in the Field of Artificial Intelligence." Courier of Kutafin Moscow State Law University (MSAL)) 1, no. 11 (January 22, 2023): 108–16. http://dx.doi.org/10.17803/2311-5998.2022.99.11.108-116.
Full textAbstract:
The article is devoted to assessing the completeness and quality of legal regulation in the field of artificial intelligence and legal support for the use of artificial intelligence in public administration. The author shows the state and development of artificial intelligence regulation in Russia.The author shows that the segments of conceptual and doctrinal and strategic planning acts and the segment of standardizing documents in Russia have been created and filled to a certain extent in the country (at least purely formally), but there are no acts of legal regulation today, neither in a full-fledged modality, nor as some starting point.The article reveals some key problems in the field of regulating the development, testing, implementation and use of artificial intelligence. The author raises the issue of separating the real developments of artificial intelligence technologies that are promising for use in public administration or are already being used or tested in this area, and outright deception in this area. The article proposes a mechanism for searching for appropriate solutions. The author proposes priority measures for completing the regulatory space in the field of artificial intelligence.
30
Zadorozhny, Оleksandr. "Demonopolization of the space industry in Ukraine." Law Review of Kyiv University of Law, no. 4 (December 30, 2020): 428–31. http://dx.doi.org/10.36695/2219-5521.4.2020.77.
Full textAbstract:
The emergence of the need to demonopolize space activities in Ukraine indicates that space may soon turn from an object ofexclusively state research into a regular destination. Therefore, we turn to the analysis of Ukrainian legislation in this area.The article analyzes the provisions of the Law of Ukraine “On Amendments to Certain Legislative Acts of Ukraine on State Regu -lation of Space Activities” and presents arguments in favor of demonopolization of space activities in Ukraine, which in turn shouldpromote space activities and attract investment in Ukraine.Historically, in Ukraine, the space industry was a state monopoly. Only scientific space research, development, testing and productionof non-rocket space objects, their repair and maintenance could be carried out by private enterprises.The basis for the abolition of the state monopoly in this area was presented by the Law of Ukraine “On Space Activities”, whichdefined the general legal basis for space activities in Ukraine, by introducing a declaration on space activities, which is essentially anotification mechanism, and abolishing registration in Space agency of concluded agreements between national and foreign privatebusiness entities.The Law of Ukraine “On Amendments to Certain Legislative Acts of Ukraine Concerning State Regulation of Space Activities”was developed to remove restrictions on such activities for private space entities, which in turn should lead to the development of spaceactivities, attracting investment in space activities. industry of Ukraine, as well as create new jobs in this area. This law is aimed atensuring development, increasing investment attractiveness, as well as creating a competitive environment for the development of thespace industry in Ukraine, both in the public and private sectors.In addition, to date, the Government has not approved a list of space activities that are subject to compulsory insurance. Thus,there is no legal basis for the implementation of this type of compulsory insurance. What leaves us an open field for discussion.
31
Feinstein, Adina D., Darryl Z. Seligman, Maximilian N. Günther, and Fred C. Adams. "Testing Self-organized Criticality across the Main Sequence Using Stellar Flares from TESS." Astrophysical Journal Letters 925, no. 1 (January 1, 2022): L9. http://dx.doi.org/10.3847/2041-8213/ac4b5e.
Full textAbstract:
Abstract Self-organized criticality describes a class of dynamical systems that maintain themselves in an attractor state with no intrinsic length or timescale. Fundamentally, this theoretical construct requires a mechanism for instability that may trigger additional instabilities locally via dissipative processes. This concept has been invoked to explain nonlinear dynamical phenomena such as featureless energy spectra that have been observed empirically for earthquakes, avalanches, and solar flares. If this interpretation proves correct, it implies that the solar coronal magnetic field maintains itself in a critical state via a delicate balance between the dynamo-driven injection of magnetic energy and the release of that energy via flaring events. All-sky high-cadence surveys like the Transiting Exoplanet Survey Satellite (TESS) provide the necessary data to compare the energy distribution of flaring events in stars of different spectral types to that observed in the Sun. We identified ∼106 flaring events on ∼105 stars observed by TESS at a 2 minute cadence. By fitting the flare frequency distribution for different mass bins, we find that all main-sequence stars exhibit distributions of flaring events similar to that observed in the Sun, independent of their mass or age. This may suggest that stars universally maintain a critical state in their coronal topologies via magnetic reconnection events. If this interpretation proves correct, we may be able to infer properties of magnetic fields, interior structure, and dynamo mechanisms for stars that are otherwise unresolved point sources.
32
Zhao, Lin, Xuesong Leng, Bowen Bai, Rui Zhao, Zeyun Cai, Jianchao He, Jin Li, and Hongsheng Chen. "Effect of Coating Thickness on the Atomic Oxygen Resistance of Siloxane Coatings Synthesized by Plasma Polymerization Deposition Technique." Coatings 13, no. 1 (January 11, 2023): 153. http://dx.doi.org/10.3390/coatings13010153.
Full textAbstract:
Atomic oxygen in the low Earth orbit (LEO) environment is highly oxidizing. Due to the high flight speed of spacecraft, the relative kinetic energy of high-flux atomic oxygen bombarding the spacecraft surface can reach up to about 5 eV. Therefore, atomic oxygen is one of the most dangerous space environment factors in LEO, which seriously affects the safe operation and service life of spacecraft in orbit. In order to meet the requirements for the high reliability and long lifetime of spacecraft, effective protection measures must be taken on their sensitive surfaces. Siloxane is a coating with an organic–inorganic hybrid structure. Compared with SiO2 and other inorganic atomic oxygen protective coatings, it has better flexibility and is better at anti-atomic oxygen performance. In this paper, the plasma polymerization deposition technique was used to prepare large-area siloxane coatings on different substrates with different thicknesses for improving atomic oxygen resistance by optimizing the process parameters. The thickness of the coating was measured by different methods, and the results showed that the thickness distribution was consistent. By observing the surface morphology of the coating, it was uniform and compact without obvious defects, so the uniformity of large-area coating was also ideal. The adhesion and heat/humidity resistance of siloxane coatings were examined by pull-off testing and damp-heat testing, respectively. The results showed that the siloxane coatings with a thickness of about 400 nm exhibited better physical properties. At the same time, the ground simulation testing of atomic oxygen confirmed that siloxane coatings with a thickness of 418 nm presented the best performance of atomic oxygen resistance. The atomic oxygen erosion yield of siloxane coatings with a thickness of 418 nm was as low as 5.39 × 10−27 cm3/atoms, which was three orders of magnitude lower than that of the uncoated Kapton substrate and presented a good anti-atomic oxygen performance. Meanwhile, it has also successfully passed the damp-heat test. The coating thickness is only several hundred nanometers and does not increase the weight of the spacecraft, which makes it a relatively ideal LEO atomic oxygen protection material. Furthermore, a possible mechanism was proposed to explicate the physicochemical process of atomic oxygen attacking the coating materials.
33
Singh, Anmol, and P. K. Jain. "A Study on Rocker-Bogie Suspension for a Planetary Rover Prototype." International Journal of Advance Research and Innovation 8, no. 3 (2020): 27–39. http://dx.doi.org/10.51976/ijari.832006.
Full textAbstract:
In light of the notable rocker-bogie mechanism, this paper shows an ideal plan of a rocker-bogie suspension framework so as to ensure high mobile steadiness as well as excellent versatility of a prototype rover vehicle while traversing through rough terrains. It is essentially a suspension arrangement utilized in mechanical automated vehicles utilized explicitly for space investigation. The rocker-bogie suspension-based rovers have been effectively presented for the Mars Pathfinder and Mars Exploration Rover (MER) and Mars Science Laboratory (MSL) missions led by zenith space investigation laboratories all through the world. The proposed suspension framework is presently the most supported structure for each space investigation organization. It is basically a mechanism which comprises of two arms with wheel mounted to each and the two arms are associated through a versatile joint. The current development in design has been studied as well as a different approach towards designing the basic structure of suspension has been done. It has been further verified using various static and dynamic load calculations, solid modelling computer aided design software and simulation software for analysis and testing.
34
Mishra, B., Eesha Gadia, and S. K. Tripathy. "Dynamics of quasi-de Sitter and linear combination of exponential models in extended gravity." International Journal of Geometric Methods in Modern Physics 18, no. 11 (June 29, 2021): 2150168. http://dx.doi.org/10.1142/s0219887821501681.
Full textAbstract:
In this paper, we have studied the dynamical aspects of some cosmological models in an isotropic space-time within the framework of an extended gravity theory. Two accelerating cosmological models are presented with quasi-de Sitter (QDS) and linear combination of exponential (LCE) scale factors. The geometrical testing mechanism has been performed and analyzed. While the results of the QDS model show a departure from the concordant [Formula: see text]CDM model, the resulting behavior of the LCE model seems to be compatible with the [Formula: see text]CDM model only at the present epoch and is incompatible in the near past.
35
Nyberg, Erik, Dídac Llopart i Cervelló, and Ichiro Minami. "Tribology in Space Robotic Actuators: Experimental Method for Evaluation and Analysis of Gearboxes." Aerospace 8, no. 3 (March 13, 2021): 75. http://dx.doi.org/10.3390/aerospace8030075.
Full textAbstract:
Liquid lubricants are critical to enable long-life operation of high-performance machinery, such as geared actuators employed in robotics. In space applications, actuator gearboxes must operate in low temperatures, where liquid lubricants face inherent problems related to low temperature rheology. Heaters are relied upon to provide acceptable gearbox temperatures. Unfortunately, heating is energy-intense and does not scale well with increasing mechanism mass and performance. Effective boundary lubrication (BL), on the other hand, can minimize problems of low temperature rheology. BL relies on tribofilm formation over conventional fluid film separation. Effective space grade boundary lubricants can potentially allow for drastically reduced amounts of oil and the accompanying rheological problems. In this work, we describe the design of a methodology to evaluate and analyze tribology of actuator gearboxes operated under cryogenic oil-starved conditions in N2 atmosphere. The devised methodology enables research pertinent to space actuator tribology by accelerated testing and advanced analysis, as demonstrated by a lubricant candidate case study. Complementary microscopy techniques are discussed, and a novel methodology devised for gear internal microstructure analysis by X-ray microtomography (XMT) is presented.
36
Shelton, Travis Edward, Dylan Joseph Stelzer, Carl R. Hartsfield, Gregory Richard Cobb, Ryan P. O'Hara, and Christopher D. Tommila. "Understanding surface roughness of additively manufactured nickel superalloy for space applications." Rapid Prototyping Journal 26, no. 3 (December 4, 2019): 557–65. http://dx.doi.org/10.1108/rpj-02-2019-0049.
Full textAbstract:
Purpose For many applications, including space applications, the usability and performance of a component is dependent on the surface topology of the additively manufactured part. The purpose of this paper is to present an investigation into minimizing the residual surface roughness of direct metal laser sintering (DMLS) samples by manipulating the input process parameters. Design/methodology/approach First, the ability to manipulate surface roughness by modifying processing parameters was explored. Next, the surface topography was characterized to quantify roughness. Finally, microthruster nozzles were created both additively and conventionally for flow testing and comparison. Findings Surface roughness of DMLS samples was found to be highly dependent on the laser power and scan speed. Because of unintended partially sintered particles adhering to the surface, a localized laser fluence mechanism was explored. Experimental results show that surface roughness is influenced by the varied parameters but is not a completely fluence driven process; therefore, a relationship between laser fluence and surface roughness can be incorporated but not completely assumed. Originality/value This paper serves as an aid in understanding the importance of surface roughness and the mechanisms associated with DMLS. Rather than exploring a more common global energy density, a localized laser fluence was initiated. Moreover, the methodology and conclusions can be used when optimizing parts via metal additive manufacturing.
37
Shams, Taimur Ali, Syed Irtiza Ali Shah, Muhammad Ayaz Ahmad, Kashif Mehmood, Waseem Ahmad, and Syed Tauqeer ul Islam Rizvi. "Selection Methodology of an Electric Actuator for Nose Landing Gear of a Light Weight Aircraft." Applied Sciences 10, no. 23 (December 6, 2020): 8730. http://dx.doi.org/10.3390/app10238730.
Full textAbstract:
Landing gear system of an aircraft enables it to take off and land with safety and comfort. Because of the horizontal and vertical velocity of aircraft, upon landing, the complete aircraft undergoes different forcing functions in the form of the impact force that is absorbed by landing gears, shock absorbers, and actuators. In this research, a selection methodology has been proposed for an electrical actuator to be installed in the retraction mechanism of nose landing gear of an aircraft having 1600 kg gross takeoff weight. Nose landing gear and its associated components, like strut and shock absorbers, were modeled in CAD software. Analytical expressions were then developed in order to calculate the actuator stroke, translational velocity, force, and power for complete cycle of retraction, and some were subsequently compared with the computational results that were obtained using MSC ADAMS®. Air in the oleo-pneumatic shock absorber of nose landing gear was modeled as a nonlinear spring with equivalent spring constant, whereas hydraulic oil was modeled as a nonlinear damper with equivalent damping constant. The nose landing gear system was modeled as a mass-spring-damper system for which a solution for sinusoidal forcing functions is proposed. Finally, an electrical actuator has been selected, which can retract and extend nose landing gear, meeting all of the constraints of aircraft, like fuselage space, aircraft ground clearance, locking loads, power consumption, retraction and extension time, and dynamic response of aircraft. It was found that the selection of an electrical actuator is based upon the quantification of forces transmitted to electrical actuator during one point load at gross takeoff weight. The ability of retraction and extension time, as dictated by Federal Aviation Regulation, has also been given due consideration in the proposed methodology as significant criteria. The proposed system is now in the process of ground testing, followed by flight testing in the near future.
38
Walsh, James C. "High Throughput, Mechanism-Based Screening Techniques for Discovering Novel Agrochemicals." Journal of Biomolecular Screening 3, no. 3 (April 1998): 175–81. http://dx.doi.org/10.1177/108705719800300303.
Full textAbstract:
A variety of screening strategies can be employed for discovering novel agrochemicals such as fungicides, insecticides, herbicides and antiparasitics. Traditionally, random evaluation of chemical and natural products samples has been used in assay systems ranging from greenhouse testing down to in vitro microplate screening. This task can be formidable depending on the size of sample libraries and personnel resources available. One important tool in the overall discovery process is the application of highly specific and sensitive mechanism-based assays for the purpose of identifying novel leads. This article describes high throughput, agar-based screening techniques successfully implemented in a decentralized screening environment where laboratory space and staffing are limited. Through the prudent use of automated and manual high-density agar-based techniques, multiple sources of samples can now be processed and evaluated against multiple targets in a timely fashion. Assay validation can be streamlined. The advantages and disadvantages of an agar-based screening approach are discussed.
39
de Groh, Kim K., James R. Gaier, Rachelle L. Hall, Matthew P. Espe, Daveen R. Cato, James K. Sutter, and Daniel A. Scheimank. "Insights into the Damage Mechanism of Teflon® FEP from the Hubble Space Telescope." High Performance Polymers 12, no. 1 (March 2000): 83–104. http://dx.doi.org/10.1088/0954-0083/12/1/307.
Full textAbstract:
Metallized Teflon® FEP (fluorinated ethylene propylene) thermal control material on the Hubble Space Telescope (HST) has been found to be degrading in the space environment. Teflon® FEP thermal control blankets (space-facing FEP) retrieved during the first servicing mission (SM1) were found to be embrittled on solar-facing surfaces and contained microscopic cracks. During the second servicing mission (SM2) astronauts noticed that the FEP outer layer of the multi-layer insulation (MLI) covering the telescope was cracked in many locations around the telescope. Large cracks were observed on the light shield, forward shell and equipment bays. A tightly curled piece of cracked FEP from the light shield was retrieved during SM2 and was severely embrittled, as witnessed by ground testing. A failure review board was organized to determine the mechanism causing the MLI degradation. Density, x-ray crystallinity and solid-state nuclear magnetic resonance (NMR) analyses of the FEP retrieved during SM1 were inconsistent with results of FEP retrieved during SM2. Because the retrieved SM2 material was curled while in space, it experienced a higher temperature extreme during thermal cycling, estimated at 200°C, than the SM1 material, estimated at 50°C. An investigation on the effects of heating pristine FEP and FEP retrieved from the HST was therefore conducted. Samples of pristine, SM1 and SM2 FEP were heated to 200°C and evaluated for changes in density and morphology. Elevated-temperature exposure was found to have a major impact on the density of the retrieved materials. The characterization of the polymer morphology of the as-received and heated FEP by NMR provided results that were consistent with the density results. Differential scanning calorimetry (DSC) was conducted on pristine, SM1 and SM2 FEP. DSC results provided evidence of chain scission and increased crystallinity in the space exposed FEP, which supported the density and NMR results. Samples exposed to simulated solar flare x-rays, thermal cycling and long-term thermal exposure provided information on the environmental contributions to degradation. These findings have provided insight into the damage mechanisms of FEP in the space environment.
40
Wang, Futao, Chaobing Li, Shaohua Niu, Pengfei Wang, Huaisong Wu, and Bingyang Li. "Design and Analysis of a Spherical Robot with Rolling and Jumping Modes for Deep Space Exploration." Machines 10, no. 2 (February 10, 2022): 126. http://dx.doi.org/10.3390/machines10020126.
Full textAbstract:
Complex and unknown terrains in deep space exploration present great challenges to existing exploration robots. In this paper, a multi-mode motion spherical robot with flexible motion and strong environmental adaptability is presented. The spherical robot can roll and jump by swinging the pendulum and rotating the 2-DOF frame. The structure design of spherical robot is described, and the feasibility of multi-mode motion is analyzed by establishing dynamic model and testing robot prototype. In addition, the adaptability of the spherical robot motion mechanism in microgravity environment is preliminarily verified. The results of this analysis and test could be provided with reference for the future research of deep space exploration robots.
41
Yang, Shu-Cheng, Wen-Biao Han, Shuo Xin, and Chen Zhang. "Testing dispersion of gravitational waves from eccentric extreme-mass-ratio inspirals." International Journal of Modern Physics D 28, no. 15 (November 2019): 1950166. http://dx.doi.org/10.1142/s0218271819501669.
Full textAbstract:
In general relativity, there is no dispersion in gravitational waves, while some modified gravity theories predict dispersion phenomena in the propagation of gravitational waves. In this paper, we demonstrate that this dispersion will induce an observable deviation of waveforms if the orbits have large eccentricities. The mechanism is that the waveform modes with different frequencies will be emitted at the same time due to the existence of eccentricity. During the propagation, because of the dispersion, the arrival time of different modes will be different, then produce the deviation and dephasing of waveforms compared with general relativity. This kind of dispersion phenomena related with extreme-mass-ratio inspirals could be observed by space-borne detectors, and the constraint on the graviton mass could be improved. Moreover, we find that the dispersion effect may also be constrained by ground detectors better than the current result if a highly eccentric intermediate-mass-ratio inspirals be observed.
42
Yu, Helong, Shimeng Qiao, Ali Asghar Heidari, Lei Shi, and Huiling Chen. "Mutational Chemotaxis Motion Driven Moth-Flame Optimizer for Engineering Applications." Applied Sciences 12, no. 23 (November 28, 2022): 12179. http://dx.doi.org/10.3390/app122312179.
Full textAbstract:
Moth-flame optimization is a typical meta-heuristic algorithm, but it has the shortcomings of low-optimization accuracy and a high risk of falling into local optima. Therefore, this paper proposes an enhanced moth-flame optimization algorithm named HMCMMFO, which combines the mechanisms of hybrid mutation and chemotaxis motion, where the hybrid-mutation mechanism can enhance population diversity and reduce the risk of stagnation. In contrast, chemotaxis-motion strategy can better utilize the local-search space to explore more potential solutions further; thus, it improves the optimization accuracy of the algorithm. In this paper, the effectiveness of the above strategies is verified from various perspectives based on IEEE CEC2017 functions, such as analyzing the balance and diversity of the improved algorithm, and testing the optimization differences between advanced algorithms. The experimental results show that the improved moth-flame optimization algorithm can jump out of the local-optimal space and improve optimization accuracy. Moreover, the algorithm achieves good results in solving five engineering-design problems and proves its ability to deal with constrained problems effectively.
43
Jiang, H., M. Wang, and M. X. Huang. "Crucial feature space for ductile bcc high-entropy alloys." Applied Physics Letters 121, no. 16 (October 17, 2022): 161902. http://dx.doi.org/10.1063/5.0124590.
Full textAbstract:
Body-centered cubic (bcc) high-entropy alloys (HEAs) are promising structural materials for nuclear power plants to ensure good radiation resistance. However, the majority of bcc HEAs show limited room temperature ductility even in compression. In addition to the compressive properties of as-cast high-activation bcc HEAs collected from the literature, those of low-activation ones were investigated by phase diagram calculations and experiments. Therefore, a consistent dataset comprising 93 samples was generated. A classification and regression tree (CART) algorithm was employed to differentiate the target bcc HEAs with a compressive failure strain of more than 50% from the others. The model generality of a finalized CART classifier was validated by training and testing F1 scores and accuracies. It was found that Pugh's ratio ( κ) and valence electron concentration ( VEC) are two key attributes to identify the target alloys. The crucial κ- VEC feature space displays that the targets are generally located in the region where κ is larger than 3.129 or VEC is larger than 6.296. Especially, high-activation and low-activation samples seem to have opposite characteristics, motivating the further study of a deformation mechanism for low-activation bcc HEAs.
44
Volkov, M. V. "Modernization of the electromechanical equipment the trigger device: description of the design and testing." Spacecrafts & Technologies 5, no. 3 (September 24, 2021): 137–45. http://dx.doi.org/10.26732/j.st.2021.3.02.
Full textAbstract:
At present, modern spacecraft use high-precision equipment that is sensitive to influence impacts. In this regard, there is a need to create shock-free trigger devices for mechanisms for holding and releasing movable structural elements. These tasks determined the vector of development of electromechanical trigger devices that do not contain pyrotechnic devices in their design. Along with the new tasks, there are constant problems of rocket and space technology – the improvement of mass-dimensional characteristics. However, pyrotechnic elements force the use of massive housings and brackets for structures that can withstand a sharp increase in pressure and the impact of the executive parts. The use of universal pyropatrons does not always allow optimizing the design of the retention mechanism. Also, one of the disadvantages of working with pyrotechnic media is the increased risk of working. The paper presents the results of a study of the possibility of modernizing the design of trigger devices, improving their mechanical and electrical characteristics. The research was carried out using calculated and experimental methods, and experimental samples of trigger devices were manufactured and released. As a result of the work, an upgraded trigger device was developed, better electrical characteristics were achieved, power consumption was reduced (the response time was reduced), mass-dimensional characteristics were improved, and the number of structural parts was reduced.
45
Li, Li, and Ji Li. "An Inverse Modeling Method for Acoustic Emission Source of Cracking." Applied Mechanics and Materials 333-335 (July 2013): 1742–45. http://dx.doi.org/10.4028/www.scientific.net/amm.333-335.1742.
Full textAbstract:
Crack formation is a severe problem concerning steel structures under service loading. Understanding of the mechanism of crack initiation and propagation is therefore critical to structure safety design and maintenance. Although many efforts were put into crack mechanism studying, and some progress has been made in the aspect of crack propagation, the problem of crack initiation i.e. cracking remains left unsolved. In this paper, an inverse modeling method for acoustic emission (AE) source of cracking was proposed for the mechanism revelation. In the method, AE signal was related to crack stress based on the theory of elasto-dynamics; the crack stress was inversely modeled from AE signal by half-space Greens function and procedure of de-convolution. In an application to the AE testing for steel structure cracking, AE source function representing the time history of crack stress was obtained. The crack stress was found to be a step-like function with a pulse, and with it the mechanism of cracking was recovered. The results indicated that, the modeling method is effective for the study on mechanism of cracking.
46
Thienyaem, Titinai, Khwantri Saengprachatanarug, Saree Wongpichet, Taira Eizo, and Prakarn Thongrak. "The Influence of the Metering Device Arrangement to the Discharging Consistency of the Sugarcane Billet Planter." Advanced Materials Research 931-932 (May 2014): 1561–67. http://dx.doi.org/10.4028/www.scientific.net/amr.931-932.1561.
Full textAbstract:
Sugar cane is an important economic crop of Thailand, used as a raw material to produce sugar and renewable energy. Due to a labor shortage problem, and an increase in the number of sugarcane combine harvesters, sugarcane billet planters from overseas have become more popular, because they can use seed cane prepared by combine harvesters. In order to maintain a high consistency of billet plating, the harvester discharge mechanism needs to accommodate the physical properties of sugarcane billet of Thai's variety, which vary by breed and harvesting method according to area. Thus, this study aims to find the appropriate arrangement of the metering devices within sugarcane billet planters which are suitable for Thai conditions. The stationary experiments were completed using a testing unit driven by an electric motor. At the initial stage the container of the testing unit was filled with 530 kg of Khon Kaen-3 sugarcane billets. The cleated conveyor belt was placed at the container wall, to act as a metering device for the testing unit. There were 3 arrangements of cleats: (1) a full width cleat, with 150mm cleat space, (2) a full width cleat, with 300mm cleat space, and (3) a half width cleat, with 300mm cleat space each side and 150mm displaced, and all were set and tested at a constant linear conveying speed of 0.2 m/s. The effects of each arrangement for discharge rates and consistency were analyzed. The results showed that the 3rd arrangement gave the best discharge consistency, with a precision index of 51.04%.
47
Zhang, Yi Zhuo, Da Yong Wang, Zhi Wei Zhou, and Shi Quan Tao. "Imaging Analysis of Image Plane Digital Holography." Advanced Materials Research 314-316 (August 2011): 1439–43. http://dx.doi.org/10.4028/www.scientific.net/amr.314-316.1439.
Full textAbstract:
Digital holography microscopy has been widely used as a testing technology in many areas for the ability of real-time three-dimensional imaging. In this study we focus on understanding the system imaging mechanism and recording capacity of the off-axis image plane digital holography (IPDH) which has several advantages. Wigner distribution function and space-bandwidth product are utilized to examine the minimum requirement for the recording capacity of the CCD camera. The discussion provides a good understanding and a useful guide to the formation of practical IPDH systems.
48
Jones, H. E., K. L. Grieve, W. Wang, and A. M. Sillito. "Surround Suppression in Primate V1." Journal of Neurophysiology 86, no. 4 (October 1, 2001): 2011–28. http://dx.doi.org/10.1152/jn.2001.86.4.2011.
Full textAbstract:
We investigated the spatial organization of surround suppression in primate primary visual cortex (V1). We utilized drifting stimuli, configured to extend either from within the classical receptive field (CRF) to surrounding visual space, or from surrounding visual space into the CRF or subdivided to generate direction contrast, to make a detailed examination of the strength, spatial organization, direction dependence, mechanisms, and laminar distribution of surround suppression. Most cells (99/105, 94%) through all cortical layers, exhibited suppression (mean reduction 67%) to uniform stimuli exceeding the CRF, and 43% exhibited a more than 70% reduction. Testing with an annulus revealed two different patterns of surround influence. Some cells (37% of cells), classical surround suppression (CSS) cells exhibited responses to an annulus encroaching on the CRF that were less than the plateau in the spatial summation curve. The majority (63%), center-gated surround suppression (CGSS) cells, showed responses to annuli that equaled or exceeded the plateau in the spatial summation curve. Analysis suggested the CSS mechanism was implemented in all cells while the CGSS mechanism was implemented in varying strength across the sample with the extreme reflected in cells that gave larger responses to annuli than to a center stimulus. Reversing the direction of motion of the portion of the stimulus surrounding the CRF revealed four different patterns of effect: no reduction in the degree of suppression (22% of cells), a reduction in surround suppression (41%), a facilitation of the response above the level to the inner stimulus alone (37%), and a facilitation of the response above that to the inner stimulus alone that also exceeded the values associated with an optimal inner stimulus. The facilitatory effects were only seen for reverse direction interfaces between the central and surrounding stimulus at diameters equal to or more than the CRF size. The zones driving the suppressive influences and the direction contrast facilitation were often spatially heterogeneous and for a number of cells bore strong comparison with the class of behavior reported for surround mechanisms in MT. This suggests a potential role, for example, in extracting information about motion contrast in the representation of the three dimensional structure of moving objects.
49
Chen, Xu, Chunhong Liu, Changchun Gao, and Yao Jiang. "Mechanism Underlying the Formation of Virtual Agglomeration of Creative Industries: Theoretical Analysis and Empirical Research." Sustainability 13, no. 4 (February 3, 2021): 1637. http://dx.doi.org/10.3390/su13041637.
Full textAbstract:
Industrial agglomeration serves as an effective model for developing the creative economy and manifests itself as the interdependence of creative subjects in geographical space. The traditional methods of resource agglomeration have undergone tremendous changes due to the development of digital technology. These transformations have given birth to a new organizational form of the virtual agglomeration of creative industries. The present work uses field interviews and grounded theoretical research methods to construct a theoretical model of this new organizational phenomenon. Questionnaire surveys and empirical testing using structural equation models are here combined to systematically analyze the formation mechanism of the virtual agglomeration of creative industries. The results show that digital technology, virtual platforms, digital creative talents, digitization of cultural resources, and government policies have driven the formation of the virtual agglomeration of creative industries. This has been achieved through network collaboration, freedom of participation, and trust guarantee mechanisms. The effect of emerging consumer demand on the virtual agglomeration of creative industries is not significant. In addition, the implications of this research are also considered and discussed.
50
Xue, Xingsi, Xiaojing Wu, Jie Zhang, Lingyu Zhang, Hai Zhu, and Guojun Mao. "Aggregating Heterogeneous Sensor Ontologies with Fuzzy Debate Mechanism." Security and Communication Networks 2021 (May 26, 2021): 1–12. http://dx.doi.org/10.1155/2021/2878684.
Full textAbstract:
Aiming at enhancing the communication and information security between the next generation of Industrial Internet of Things (Nx-IIoT) sensor networks, it is critical to aggregate heterogeneous sensor data in the sensor ontologies by establishing semantic connections in diverse sensor ontologies. Sensor ontology matching technology is devoted to determining heterogeneous sensor concept pairs in two distinct sensor ontologies, which is an effective method of addressing the heterogeneity problem. The existing matching techniques neglect the relationships among different entity mapping, which makes them unable to make sure of the alignment’s high quality. To get rid of this shortcoming, in this work, a sensor ontology extraction method technology using Fuzzy Debate Mechanism (FDM) is proposed to aggregate the heterogeneous sensor data, which determines the final sensor concept correspondences by carrying out a debating process among different matchers. More than ever, a fuzzy similarity metric is presented to effectively measure two entities’ similarity values by membership function. It first uses the fuzzy membership function to model two entities’ similarity in vector space and then calculate their semantic distance with the cosine function. The testing cases from Bibliographic data which is furnished by the Ontology Alignment Evaluation Initiative (OAEI) and six sensor ontology matching tasks are used to evaluate the performance of our scheme in the experiment. The robustness and effectiveness of the proposed method are proved by comparing it with the advanced ontology matching techniques.