Dynamic Characteristics Measurement of Silicon Micro-Cantilever in Low Temperature Environment

2011 ◽  
Vol 483 ◽  
pp. 18-22
Author(s):  
Dong Sheng She ◽  
Xiao Dong Wang ◽  
Xi Wen Zhang ◽  
Li Ding Wang
Keyword(s):  
Low Temperature ◽  
Room Temperature ◽  
Dynamic Testing ◽  
Laser Doppler Vibrometer ◽  
Impact Excitation ◽  
Testing System ◽  
Resonance Frequencies ◽  
Temperature Environment ◽  
Micro Cantilever ◽  
Driving Source

The dynamic testing system for MEMS in low temperature environment has been developed. A thermoelectric cooling refrigerator was utilized to generate the low temperature environment. The base excitation device was established using the piezoelectric ceramic as the driving source. A vacuum chamber was designed to protect the micro-structure from the humid air. Through the base impact excitation, the resonance frequencies are obtained by analyzing the impulse response signals. The frequency response of micro-cantilever was obtained by using both BIST method and laser Doppler vibrometer. The dynamic testing experiments for the silicon micro-cantilever were carried out from -50°C to room temperature. The result shows that the resonance frequency slightly increases with the decreasing temperature. The measurement device is effective to carry out dynamic testing of microstructure from -50°C to room temperature.

Chlorine Nuclear Quadrupole Relaxation Studies on Ionic Dynamics and Phase Transition in NH4AUCl4

1990 ◽  
Vol 45 (3-4) ◽  
pp. 467-471 ◽  
Author(s):  
Atsushi Ishikawa ◽  
Tetsuo Asaji ◽  
Daiyu Nakamura
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Room Temperature ◽  
Complex Anion ◽  
Relaxation Times ◽  
Quadrupole Relaxation ◽  
Spin Lattice ◽  
Resonance Frequencies ◽  
Disorder Type ◽  
Nuclear Quadrupole Relaxation

Abstract Chlorine NQR frequencies, and NQR spin-lattice and spin-spin relaxation times (T1Q and T2Q) were measured for NH4AuCl4 crystals at various temperatures between 4.2 and 337 K. Each of the two resonance lines observed at room temperature is split into a doublet below Tc = 29 K, indicating a phase transition. A rapid decrease of T1Q above ca. 290 K is attributable to 90° reorientational jumps of the complex anion about its pseudo C4 axis. An activation energy of 80 kJ mol -1 was obtained for this motion. 35Cl T1Q exhibits a minimum at Tc . The T1Q isotope ratio T1Q (37Cl)/ T1Q (35Cl) becomes 1.6 and 1.0 on the high-and low-temperature sides of this minimum, respectively. These results were explained by fluctuations of the electric field gradient produced at the chlorine nuclei by the reorientational jumps of the NH+4 ions. The motion of the cations is much faster and much slower than the resonance frequencies on the high-and low-temperature sides, respectively. This suggests that the phase transition is of the order-disorder type relating to the orientation of the NH+4 ion.

Modeling, Fabrication and Characterization of Piezoelectric ZnO-Based Micro-Sensors and Micro-Actuators

2013 ◽  
Vol 444-445 ◽  
pp. 1636-1643 ◽  
Author(s):  
Yan Hui Yuan ◽  
He Jun Du ◽  
Xin Xia ◽  
Yoke Rung Wong
Keyword(s):  
Thin Film ◽  
Room Temperature ◽  
Laser Doppler Vibrometer ◽  
Zno Thin Film ◽  
Design Specifications ◽  
Piezoelectric Cantilever ◽  
Fabrication And Characterization ◽  
Micro Cantilever ◽  
Microfabrication Techniques

In this study, capabilities of zinc oxide (ZnO) thin films in sensing and actuating were investigated using micromachined micro-cantilevers. A heterogeneous piezoelectric cantilever was modeled to study its response under voltage and/or external mechanical loading. A ZnO thin-film micro-cantilever was designed based on the developed theoretical model. Simulated tip deflections of the micro-cantilever were on the nanometer level under typical electrical and mechanical input. A prototype was fabricated with microfabrication techniques. The ZnO thin film was sputtered at room temperature and demonstrated good compatibility with common chemicals and processes in micromachining. The fabricated micro-cantilever was experimentally characterized for its actuating and sensing performance. For actuator characterization tip deflection of the micro-cantilever was detected by a laser Doppler vibrometer, while for sensor characterization the micro-cantilever was calibrated as an acceleration sensor using a reference accelerometer. The experimental resonant frequency, actuating and sensing sensitivities agreed well the design specifications.

scholarly journals Low Temperature Influence on the Behavior of Viscoelastic Layer of the Pounding Tuned Mass Damper

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3986 ◽  
Author(s):  
Peng Zhang ◽  
Jinwei Jiang ◽  
Guangtao Lu
Keyword(s):  
Energy Dissipation ◽  
Low Temperature ◽  
Viscoelastic Material ◽  
Room Temperature ◽  
Cyclic Hardening ◽  
Tuned Mass Damper ◽  
Mass Damper ◽  
Temperature Environment ◽  
Softening Process ◽  
The Impact

In previous studies, the pounding tuned mass damper (PTMD) has been successfully demonstrated to mitigate the undesired vibration of a variety of structures at room temperature. The advantages of the PTMD over the traditional tuned mass damper (TMD) has been verified through theoretical analysis and experimental investigations. However, the PTMD relies on an impact layer made of viscoelastic material to improve its vibration control performance and robustness against detuning effect. The energy dissipation of the viscoelastic material can be affected by the changes of environmental temperature. Therefore, this paper aims to study the impact damping behavior of the viscoelastic material in the low temperature environment of the sea bed where the PTMD is expected to control vibrations of subsea pipelines. The experimental apparatus fabricated in the previous study to generate and measure the lateral impact was housed inside a refrigerator. The experimental results indicate that the pounding stiffness decreased whereas the energy dissipation increased in the low temperature environment. Moreover, an impact fatigue test was also performed in the low temperature environment and compared with the room temperature case. Experimental results from a previous study show that the viscoelastic material was damaged after 36,000 cycles of impacts in the room temperature and a cyclic hardening–softening process was observed. However, in the low temperature environment, the viscoelastic material was damaged after 50,000 cycles of impacts and the cyclic hardening–softening process was not observed. As the impact cycle grew, the pounding stiffness decreased from 53,000 N/m1.5 to 17,000 N/m1.5 and the energy dissipation increased from 46.12 J/m per cycle to 65.4 J/m per cycle.

scholarly journals The Effects ofPanax ginsengandPanax quinquefoliuson Thermoregulation in Animal Models

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Bin Na Hong ◽  
Moon Ho Do ◽  
You Ri Her ◽  
Yeong Ro Lee ◽  
Tong Ho Kang
Keyword(s):  
Body Temperature ◽  
Animal Models ◽  
Low Temperature ◽  
Temperature Change ◽  
Room Temperature ◽  
The Body ◽  
Panax Quinquefolius ◽  
Control Group ◽  
Body Temperature Change ◽  
Temperature Environment

We devised a study using animal models of hyperthermia and hypothermia and also attempted to accurately assess the effects ofPanax ginseng(PG) andPanax quinquefolius(PQ) on body temperature using these models. In addition, we investigated the effects of PG and PQ in our animal models in high and low temperature environments. The results of our experiments show that mice with normothermia, hyperthermia, and hypothermia maintained their body temperatures after a certain period in accordance with the condition of each animal model. In our experiments of body temperature change in models of normal, low, or high room temperature, the hyperthermic model did not show any body temperature change in either the PG- or PQ-administered group. In the normal and low room temperature models, the group administered PG maintained body temperature, while the body temperature of the PQ-administered group was lower than or similar to that of the control group. In conclusion, the fact that PG increases body temperature could not be verified until now. We also showed that the effect of maintaining body temperature in the PG-administered group was superior in a hypothermia-prone low temperature environment.

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.

scholarly journals Research on Performance Test System of Space Harmonic Reducer in High Vacuum and Low Temperature Environment

Machines ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 1
Author(s):  
Jing Wang ◽  
Zhihua Wan ◽  
Zhurong Dong ◽  
Zhengguo Li
Keyword(s):  
Low Temperature ◽  
High Speed ◽  
Performance Test ◽  
High Reliability ◽  
High Vacuum ◽  
Test System ◽  
Low Noise ◽  
Speed Ratio ◽  
Space Harmonic ◽  
Temperature Environment

The harmonic reducer, with its advantages of high precision, low noise, light weight, and high speed ratio, has been widely used in aerospace solar wing deployment mechanisms, antenna pointing mechanisms, robot joints, and other precision transmission fields. Accurately predicting the performance of the harmonic reducer under various application conditions is of great significance to the high reliability and long life of the harmonic reducer. In this paper, a set of automatic harmonic reducer performance test systems is designed. By using the CANOpen bus interface to control the servo motor as the drive motor, through accurately controlling the motor speed and rotation angle, collecting the angle, torque, and current in real time, the life cycle test of space harmonic reducer was carried out in high vacuum and low temperature environment on the ground. Then, the collected data were automatically analyzed and calculated. The test data of the transmission accuracy, backlash, and transmission efficiency of the space harmonic reducer were obtained. It is proven by experiments that the performance data of the harmonic reducer in space work can be more accurately obtained by using the test system mentioned in this paper, which is convenient for further research on related lubricating materials.

scholarly journals Analysis of Mechanical Properties and Mechanism of Natural Rubber Waterstop after Aging in Low-Temperature Environment

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2119
Author(s):  
Lin Yu ◽  
Shiman Liu ◽  
Weiwei Yang ◽  
Mengying Liu
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Energy Dispersive Spectrometry ◽  
Permanent Deformation ◽  
Test Chamber ◽  
Accelerate Aging ◽  
Aging Mechanism ◽  
Temperature Environment ◽  
Freezing Test ◽  
Temperature Water

In order to elucidate the aging performance and aging mechanism of a rubber waterstop in low-temperature environments, the rubber waterstops were placed in the freezing test chamber to accelerate aging, and then we tested its tensile strength, elongation, tear strength, compression permanent deformation and hardness at different times. Additionally, the damaged specimens were tested by scanning electron microscope, Fourier transform infrared spectroscopy and energy dispersive spectrometry. The results showed that with the growth of aging time, the mechanical properties of the rubber waterstop are reduced. At the same time, many protrusions appeared on the surface of the rubber waterstop, the C element gradually decreased, and the O element gradually increased. During the period of 72–90 days, the content of the C element in the low-temperature air environment significantly decreased compared with that in low-temperature water, while the content of O element increased significantly.

Photophysical properties of N719 and Z907 dyes, benchmark sensitizers for dye-sensitized solar cells, at room and low temperature

2021 ◽  
Vol 23 (10) ◽  
pp. 6182-6189
Author(s):  
Dariusz M. Niedzwiedzki
Keyword(s):  
Solar Cells ◽  
Low Temperature ◽  
Optical Spectroscopy ◽  
Room Temperature ◽  
Photophysical Properties ◽  
Dye Sensitized Solar Cells ◽  
Time Resolved ◽  
Dye Sensitized ◽  
Sensitized Solar Cells

Photophysical properties of N719 and Z907, benchmark Ru-dyes used as sensitizers in dye-sensitized solar cells, were studied by static and time-resolved optical spectroscopy at room temperature and 160 K.

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