Force Sensor Characterization Under Sinusoidal Excitations
The aim in the current work is the development of a method to characterize force sensors under sinusoidal excitations using a primary standard as the source of traceability. During this work the influence factors have been studied and a method to minimise their contributions, as well as the corrections to be performed under dynamic conditions have been established. These results will allow the realization of an adequate characterization of force sensors under sinusoidal excitations, which will be essential for its further proper use under dynamic conditions. The traceability of the sensor characterization is based in the direct definition of force as mass multiplied by acceleration. To do so, the sensor is loaded with different calibrated loads and is maintained under different sinusoidal accelerations by means of a vibration shaker system that is able to generate accelerations up to 100 m/s2 with frequencies from 5 Hz up to 2400 Hz. The acceleration is measured by means of a laser vibrometer with traceability to the units of time and length. A multiple channel data acquisition system is also required to simultaneously acquire the electrical output signals of the involved instrument in real time.
NIST 1-KILONEWTON SINE FORCE CALIBRATION SYSTEM
Many force-measurement applications are of a dynamic nature, and in recent decades there has been much progress in demonstrating and developing dynamic calibration systems for force transducers. The National Institute of Standards and Technology (NIST), U.S.A., is developing a system for sinusoidal calibration of force transducers with forces up to 1 kilonewton at frequencies up to 2 kilohertz, in a manner that is traceable to the International System of Units (SI). The system is based on harmonic excitation of a calibrated mass ( m ) using an electrodynamic shaker, laser interferometric measurement of acceleration ( a ), and voltage measurement using a calibrated fast digital voltmeter. The output voltage from a force transducer system under calibration is indexed against the input force given by F = m · a . The design and operation of the system are described.
Endovascular Stent Can Be the Treatment of Choice for Spontaneous Iliac Vein Rupture: A Case Report
Introduction: Spontaneous iliac vein rupture is a rare but lethal disease. Most patients suffer from shock status in the emergency department. Until now, open laparotomy combined with primary suture is the most common treatment of iliac vein rupture. However, there is high mortality and morbidity in the patients who underwent open laparotomy. Case Presentation: A 71-year-old woman denied trauma history and sustained hypovolemic shock. The abdominal computed tomography showed one huge retroperitoneal hematoma. The emergency angiography revealed one obvious rupture point on the left external iliac vein. We repaired the lesion with endovascular stent and open laparotomy for abdominal decompression. The patient progressed well and was discharged. Conclusion: Endovascular repair is an effective and safe treatment. Compared with open laparotomy and primary suture, stent leads to fewer complications and a lower mortality rate.