Numerical modeling of impacts of twisted-pair data cables

2019 ◽  
Author(s):  
Joshua E. Miller
Keyword(s):  
Experimental Work ◽  
Short Circuit ◽  
Space Station ◽  
Outer Diameter ◽  
Twisted Pair ◽  
Impact Location ◽  
Copper Shield ◽  
Detailed Assessment ◽  
Reliability Assessments ◽  
Impact Simulations

Abstract Data wire cable runs are a significant presence on the exterior of the International Space Station (ISS), and continued ISS mission support requires detailed assessment of cables due to micrometeoroid and orbit debris (MMOD) impact. These data wire cables are twisted-pair cables consisting of two 22 gauge stranded conductors inside a tight-fitting, braided-copper shield and jacket having a nominal outer diameter of 3.76 mm. Previous work has documented a total of 97 impact experiments that were performed into these cables to develop an empirical, statistical model for the failure of these cables in reliability studies; however, the experimental work left open the internal behaviors that contribute to the probabilistic findings. To address this shortcoming, numerical impact simulations have been performed to expand the understanding of the acquired dataset. This paper summarizes the dependence of impact location and speed to the penetration of wire jackets based upon particle size and provides an empirical ballistic limit equation based on the assumption that exposed conductors may lead to a short circuit. This work is consolidated with the previous experimental work for design and reliability assessments to cover projectile types, speeds and obliquities.

Experimental Determination of the Static Equivalent Pressures of Detonative Explosions of Stoichiometric H2/O2/N2-Mixtures in Long and Short Pipes

2015 ◽  
Author(s):  
Hans-Peter Schildberg
Keyword(s):  
Experimental Determination ◽  
Flame Front ◽  
Wall Thickness ◽  
Experimental Work ◽  
Gas Mixtures ◽  
Outer Diameter ◽  
Auto Ignition

As continuation of recently published experimental work [1,2], the static equivalent pressures (“pstat“) of the different detonative pressure scenarios occurring in stoichiometric H2/O2/N2 mixtures were determined in long and short pipes at ambient initial temperatures (20 °C) and initial pressures ranging from 4 bar abs to 35 bar abs. The pipes used for the tests were about 10 m long and had radial dimensions of 48.3×2.6 and 114.3×3.6 (outer diameter [mm] × wall thickness [mm]). The O2 content was varied from about 10 vol.-% to the highest value possible in stoichiometric mixtures (33.3 vol.-%). For the tests in the long pipes the focus was on the variation of the ratio between the static equivalent pressure at the point where transition from deflagration to detonation occurred and the static equivalent pressure in the region of the stable detonation (pstat_DDT_long / pstat_stable). The ratio attained a maximum of about 5 at 14.78 vol.-% O2 (stoichiometric H2/air) and decays to 1 when increasing the O2 content to 24 vol.-%. This drop indicates that with increasing O2 content ever less precompression is required to cause auto ignition in the precompressed gas directly ahead of the deflagrative flame front. For mixtures of H2 with N2-diluted air the ratio exhibits a slight decrease which is in contrast to what would be expected and is not yet understood. The results obtained for the ratio between pstat of scenarios 3 and 4 (stable detonation and reflected stable detonation) and the Chapman-Jouguet pressure of the investigated gas mixtures confirmed the findings presented in PVP2013-97677 for ethylene/air-mixtures. For mixtures of H2 and slightly diluted air the load for the reflected instable detonation was found to be about 7 · pstat_stable, the load at the DDT in the short pipe is 6.6 · pstat_stable and the load for coalescence of DDT and reflection is about 14 · pstat_stable.

scholarly journals Towards Determination of Inductive Resistances of Single-Core Cables with Voltage of up to 1 kV Insulated by Cross-Linked Polyethylene

2018 ◽  
Vol 61 (4) ◽  
pp. 321-333
Author(s):  
V. N. Radkevich ◽  
V. V. Stalovich ◽  
D. S. Alekhnovich
Keyword(s):  
Proximity Effect ◽  
Reactive Power ◽  
Surface Effect ◽  
Short Circuit ◽  
Outer Diameter ◽  
Electrical Networks ◽  
Technical Literature ◽  
Significant Difference ◽  
Cable Lines

To calculate short-circuit currents, voltage losses and reactive power in electrical networks, information on inductive resistances of cable lines is required. In the technical literature there are no exact parameters of single-core cables with voltage of up to 1 kV insulated by crosslinked polyethylene. This results in inaccuracies in the calculations of modes of electrical networks. The article considers the issues of determining the inductance and inductive resistance of power lines up with voltage of up to 1 kV made of single-core cables and insulated by crosslinked polyethylene. The analysis of formulas for determining the inductance given in different literature sources was fulfilled, that demonstrated a significant difference in the numerical values of the obtained calculation results. The formula that provides more reliable calculations of the inductance of the cable lines was identified. The influence of the permissible increase in the thickness of the insulation and the sheath of a single-core cable with voltage of up to 1 kV covered with cross-linked polyethylene on the inductive resistance was determined. The inductance and inductive resistance of single-core cables were calculated when the cables were arranged along the vertices of an equilateral and right-angle triangle, as well as in one plane. It was shown that the specific inductances and inductive resistances are 1.7–1.8 times greater in the plane with the distance between adjacent cables equal to the outer diameter of the cable than in the location is close to the triangle. When the cross sections of conductive cores are large and installations are multi-ampere, there is a surface effect and proximity effect, due to which the magnetic field intensity inside the core and its inductance decrease. Inductivities and inductive resistances of singlecore cables with voltage up to 1 kV were determined taking into account the influence of the surface effect and the proximity effect. The calculations that we performed have shown that the nonconsideration of the above-mentioned effects leads to significant errors in the determination of inductive resistances. The influence of one-core cables of armor made of steel tapes on inductive resistances is considered. An illustrative example shows that the inductive resistance of an armored cable with a cross-section area of the current-conducting core equal to 800 mm2 is about twice as large as the unarmored one. The use of single-core cables in three-phase electrical networks, armored with steel straps, ought to be prohibited by regulatory documents, since such cables dramatically worsen the efficiency of power supply systems.

Fracture Assessment of X65 Steel Pipe With Through-Wall Crack Under Pure Bending

2013 ◽  
Author(s):  
A.-H. I. Mourad ◽  
J. Altarawneh ◽  
A. El Domiaty
Keyword(s):  
Crack Growth ◽  
Experimental Work ◽  
Steel Pipe ◽  
Outer Diameter ◽  
Pure Bending ◽  
Unstable Crack ◽  
Critical Crack ◽  
Steel Pipes ◽  
X65 Steel ◽  
Fracture Assessment

Stable crack growth emanated from circumferential through-wall crack in X65 steel pipe under pure bending was evaluated. Seamless carbon steel pipes grade X65 PL5 with an inner diameter of 42.9 mm and an outer diameter of 60.3 mm were used in the present experimental work. This type of pipes is of common use in piping systems of gas and oil industry. Pipes of different circumferential crack depths were tested. J-R curve was used to characterize the nonlinear fracture behavior of the through-wall crack pipe. Variation of J with crack growth, crack surface area and deflection of the pipe were obtained. J-integral-crack growth curve was used in the calculation of critical crack size based on the Jc value measured in our previous experimental work by testing full scale pipe made from the same material. The length of crack at unstable crack growth is also determined. Both critical and instability crack sizes can be used for fracture assessment of X65 steel pipes.

Structural Imperfections in thin Oxide Films Formed on Some Fe- and Ni-Base Alloys

1970 ◽  
Vol 28 ◽  
pp. 510-511
Author(s):  
L. P. Lemaire ◽  
D. E. Fornwalt ◽  
F. S. Pettit ◽  
B. H. Kear
Keyword(s):  
Oxide Scale ◽  
Oxidation Process ◽  
Short Circuit ◽  
Protective Oxide ◽  
Protective Oxide Scale ◽  
Thin Oxide Films ◽  
Diffusion Paths ◽  
Oxidation Resistant ◽  
Structural Imperfections ◽  
Short Circuit Diffusion

Oxidation resistant alloys depend on the formation of a continuous layer of protective oxide scale during the oxidation process. The initial stages of oxidation of multi-component alloys can be quite complex, since numerous metal oxides can be formed. For oxidation resistance, the composition is adjusted so that selective oxidation occurs of that element whose oxide affords the most protection. Ideally, the protective oxide scale should be i) structurally perfect, so as to avoid short-circuit diffusion paths, and ii) strongly adherent to the alloy substrate, which minimizes spalling in response to thermal cycling. Small concentrations (∼ 0.1%) of certain reactive elements, such as yttrium, markedly improve the adherence of oxide scales in many alloy systems.

Structure of rattlesnake venom lectin determined by single particle high-resolution electron microscopy

1996 ◽  
Vol 54 ◽  
pp. 62-63
Author(s):  
Peter D. Moisiuk ◽  
Daniel R. Beniac ◽  
Ross A. Ridsdale ◽  
Martin Young ◽  
Bhushan Nagar ◽  
...  
Keyword(s):  
High Resolution Electron Microscopy ◽  
Lipid Monolayer ◽  
Outer Diameter ◽  
X Ray Diffraction ◽  
Single Particles ◽  
Crotalus Atrox ◽  
3D Reconstructions ◽  
X Ray ◽  
Rattlesnake Venom ◽  
Covalently Linked

Venom from the rattlesnake Crotalus atrox contains a mixture of enzymes that induce a localized effect leading to hemorrhaging, necrosis and edema. As a member of the crotalid family of snake venoms, Crotalus atrox venom contains a C-type lectin that will agglutinate blood cells in a Ca2+-dependent fashion. The lectin is a hydrophilic protein, consisting of two covalently linked, 135 amino acid residues, identical subunits that are rich in aspartic acid, glutamic acid and lysine. Sequence homology with known carbohydrate recognition domains (CRDs) indicates that rattlesnake venom lectin (RSLV) contains a CRD motif that is not linked to accessory domains. Preliminary X-ray diffraction and sedimentation analysis has indicated that lectin from Crotalus atrox forms decamers composed of two five-fold symmetric pentamers. Single particles of RSVL imaged at – 171°C displayed two distinct orientations on the specimen support (Figure a) following incubation in a crystallization Teflon well, coated with a lipid monolayer consisting of phosphatidylcholine and monosialoganglioside. When lying in an end-on orientation, the lectin exhibited a “pentagonal ring” with an outer diameter of 6.7 nm and an inner hollow core of 1.7 nm. A side orientation was also seen, whereby a thickness of 5.8 nm was measured for the lectin. Image processing of 2280 single particles placed in 100 classes (Figure b) led to 3D reconstructions of RSVL (Figure c). Density limited 3D reconstructions showed the lectin to be made of two five-fold symmetrical rings covalently linked between the five subunits that constitute each ring of this homodimer. These results are consistent with sedimentation and preliminary X-ray diffraction analysis on the shape of RSVL and provide the framework for structural verification by 2D electron crystallography.

Duet: A distributed usability lab supporting displays development for space station

1999 ◽  
Author(s):  
H. Charles Dischinger ◽  
Neal C. Tilghman ◽  
Matthew Hammons ◽  
Joseph P. Hale
Keyword(s):  
Space Station
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