Hydromechanical Analysis of Fluid–Elastomeric Lag Dampers Including Subzero Temperatures

2014 ◽  
Vol 51 (3) ◽  
pp. 1056-1061 ◽  
Author(s):  
Grum T. Ngatu ◽  
Harinder J. Singh ◽  
Norman M. Wereley ◽  
Curt S. Kothera
Keyword(s):  
Subzero Temperatures ◽  
Hydromechanical Analysis ◽  
Lag Dampers

Survival of mouse blastocysts after low-temperature preservation under high pressure

2004 ◽  
Vol 52 (4) ◽  
pp. 479-487 ◽  
Author(s):  
Cs. Pribenszky ◽  
M. Molnár ◽  
S. Cseh ◽  
L. Solti
Keyword(s):  
Phase Transition ◽  
Hydrostatic Pressure ◽  
Low Temperature ◽  
High Hydrostatic Pressure ◽  
Room Temperature ◽  
Freezing Point ◽  
Significant Loss ◽  
Embryo Cryopreservation ◽  
Subzero Temperatures ◽  
Survival Capacity

Cryoinjuries are almost inevitable during the freezing of embryos. The present study examines the possibility of using high hydrostatic pressure to reduce substantially the freezing point of the embryo-holding solution, in order to preserve embryos at subzero temperatures, thus avoiding all the disadvantages of freezing. The pressure of 210 MPa lowers the phase transition temperature of water to -21°C. According to the results of this study, embryos can survive in high hydrostatic pressure environment at room temperature; the time embryos spend under pressure without significant loss in their survival could be lengthened by gradual decompression. Pressurisation at 0°C significantly reduced the survival capacity of the embryos; gradual decompression had no beneficial effect on survival at that stage. Based on the findings, the use of the phenomena is not applicable in this form, since pressure and low temperature together proved to be lethal to the embryos in these experiments. The application of hydrostatic pressure in embryo cryopreservation requires more detailed research, although the experience gained in this study can be applied usefully in different circumstances.

BERYLCO 25S

Alloy Digest ◽  
1952 ◽  
Vol 1 (3) ◽  
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Precipitation Hardening ◽  
Elevated Temperatures ◽  
Heat Treating ◽  
Good Resistance ◽  
Subzero Temperatures ◽  
Endurance Strength ◽  
Wear And Corrosion ◽  
Resistance To Wear

Abstract Berylco 25S alloy is the high-performance beryllium-copper spring material of 2 percent nominal beryllium content. It responds to precipitation-hardening for maximum mechanical properties. It has high elastic and endurance strength, good electrical and thermal conductivity, excellent resistance to wear and corrosion, high corrosion-fatigue strength, good resistance to moderately elevated temperatures, and no embrittlement or loss of normal ductility at subzero temperatures. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Cu-3. Producer or source: Beryllium Corporation.

2 1/4% NICKEL STEEL

Alloy Digest ◽  
1980 ◽  
Vol 29 (11) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
Brittle Fracture ◽  
Physical Properties ◽  
Heat Treating ◽  
Pressure Vessels ◽  
Nickel Steel ◽  
Subzero Temperatures ◽  
Steel Mills ◽  
Resistance To Brittle Fracture

Abstract The 21/4% Nickel Steel possesses a combination of moderate strength and superior resistance to brittle fracture at subzero temperatures. It is one of the most economical materials for the construction of equipment to operate at temperatures as low as -90 F. It is intended primarily for welded pressure vessels. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SA-378. Producer or source: Alloy steel mills and foundries.

TRI-MARK TM-811N2

Alloy Digest ◽  
1983 ◽  
Vol 32 (4) ◽  
Keyword(s):  
Low Temperature ◽  
High Strength ◽  
Heat Treating ◽  
Low Alloy Steels ◽  
Nickel Steel ◽  
Fine Grained ◽  
Subzero Temperatures ◽  
Steel Weld Metal ◽  
Alloy Steels ◽  
Welding Electrode

Abstract TRI-MARK TM-811N2 is a flux-cored welding electrode for all position semiautomatic arc welding. It is designed to weld 2-3% nickel steels for applications requiring good toughness at subzero temperatures; in addition, it is used to weld various other high-strength low-alloy steels and various fine-grained steels with low-temperature toughness. Tri-Mark TM-811N2 is used to deposit typically 2.35% nickel steel weld metal with good low-temperature impact properties. It is used for shipbuilding, oil rigs and similar structures. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as heat treating, machining, and joining. Filing Code: SA-389. Producer or source: Tri-Mark Inc..

Supercooling Points of Adult Dermacentor variabilis (Acari: Ixodidae) From a Population Near the Northern Distribution Limit

2020 ◽  
Author(s):  
Matthew E M Yunik ◽  
Neil B Chilton
Keyword(s):  
Cold Hardiness ◽  
Dermacentor Variabilis ◽  
Subzero Temperatures ◽  
Host Seeking ◽  
Short Period ◽  
Significant Difference ◽  
Northern Distribution ◽  
Dog Tick ◽  
Provincial Park ◽  
Established Population

Abstract The northern distributional limit of Dermacentor variabilis Say, the American dog tick, is expanding in Saskatchewan and Manitoba (western Canada). The ability of D. variabilis to continue to expand its range northwards will depend upon the ability of individuals within populations at the species distributional edge to withstand very low temperatures during winter. One component of cold hardiness is the supercooling point (SCP), the temperature below 0°C at which an individual freezes. In this study, the SCP was determined for 94 questing D. variabilis adults (44 females and 50 males) from an established population near Blackstrap Provincial Park in Saskatchewan. SCP values ranged from −18.2 to −6.7°C, with a median of −13.3°C. This suggests that host-seeking D. variabilis adults differ in their ability to survive exposure to subzero temperatures, for at least a short period of time, without freezing. The distribution of SCPs was bimodal, but there was no significant difference in SCP values between female and male ticks, and no relationship between SCP and tick body weight. It remains to be determined what factors contribute to the variation in SCP values among questing D. variabilis adults.

scholarly journals Low-Temperature Mechanical Properties of High-Density and Low-Density Polyethylene and Their Blends

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1821
Author(s):  
Ildar I. Salakhov ◽  
Nadim M. Shaidullin ◽  
Anatoly E. Chalykh ◽  
Mikhail A. Matsko ◽  
Alexey V. Shapagin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Impact Strength ◽  
Relative Elongation ◽  
High Density ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Elongation At Break ◽  
Subzero Temperatures ◽  
Izod Impact

Low-temperature properties of high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and their blends were studied. The analyzed low-temperature mechanical properties involve the deformation resistance and impact strength characteristics. HDPE is a bimodal ethylene/1-hexene copolymer; LDPE is a branched ethylene homopolymer containing short-chain branches of different length; LLDPE is a binary ethylene/1-butene copolymer and an ethylene/1-butene/1-hexene terpolymer. The samples of copolymers and their blends were studied by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), 13С NMR spectroscopy, and dynamic mechanical analysis (DMA) using testing machines equipped with a cryochamber. It is proposed that such parameters as “relative elongation at break at −45 °C” and “Izod impact strength at −40 °C” are used instead of the ductile-to-brittle transition temperature to assess frost resistance properties because these parameters are more sensitive to deformation and impact at subzero temperatures for HDPE. LLDPE is shown to exhibit higher relative elongation at break at −45 °C and Izod impact strength at −20 ÷ 60 °C compared to those of LDPE. LLDPE terpolymer added to HDPE (at a content ≥ 25 wt.%) simultaneously increases flow properties and improves tensile properties of the blend at −45 °C. Changes in low-temperature properties as a function of molecular weight, MWD, crystallinity, and branch content were determined for HDPE, LLDPE, and their blends. The DMA data prove the resulting dependences. The reported findings allow one to understand and predict mechanical properties in the HDPE–LLDPE systems at subzero temperatures.

Ultrahigh capacity and cyclability of dual-phase TiO2 nanowires with low working potential at room and subzero temperatures

2021 ◽  
Author(s):  
Dongmei Lin ◽  
Linlong Lyu ◽  
Kaikai Li ◽  
Guohua Chen ◽  
Haimin Yao ◽  
...  
Keyword(s):  
Lithium Ion Battery ◽  
High Voltage ◽  
Lithium Ion ◽  
Dual Phase ◽  
Tio2 Nanowires ◽  
Subzero Temperatures

The commercialization of TiO2 materials for lithium-ion battery (LIB) anodes has been seriously limited due to unsatisfactory capacities and high voltage plateaus vs Li/Li+ (~ 1.75 V). In this work,...

Suppression of ground resonance in rotorcraft using active landing gear

2021 ◽  
pp. 095441002110230
Author(s):  
Arjun Krishnan ◽  
Ashwin Krishnan ◽  
Mark Costello
Keyword(s):  
Optimal Control ◽  
Control Mechanism ◽  
Landing Gear ◽  
Superior Performance ◽  
Physical Parameters ◽  
Mechanical Instability ◽  
Ground Resonance ◽  
Excited Oscillation ◽  
Lq Optimal Control ◽  
Lag Dampers

This article examines the fundamental aspects of controlling ground resonance in rotorcraft equipped with actively controlled landing gear. Ground resonance is a mechanical instability affecting rotorcraft on the ground. It occurs at certain rotor speeds, where the lead–lag motion of the rotor couples with the motion of fuselage creating a self-excited oscillation. Typically, passive or semi-active lag dampers are used to avoid instability; however, these are undesirable from a design and maintenance perspective. Innovations in active landing gear for rotorcraft, such as articulated robotic legs, have provided an alternate approach to avoid the instability, eliminating the need for lag dampers with respect to ground resonance. This article extends classic ground resonance to include movable landing gear and identifies key physical parameters affecting dynamic behavior. Applying LQ optimal control to this model, it is shown that ground resonance instability can be eliminated using active landing gear as the control mechanism, even when there is no lag damping present in the rotor. In addition, while superior performance is achieved when landing gear movement can occur both longitudinally and laterally, it is still possible to stabilize ground resonance with inputs in a single direction, albeit with reduced performance.

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