The Global Positioning System (GPS) is a worldwide navigation system that requires a clear line of sight to the orbiting satellites. For land vehicle navigation, a clear line of sight cannot be maintained all the time as the vehicle can travel through tunnels, under bridges, forest canopies or within urban canyons. In such situations, the augmentation of GPS with other systems is necessary for continuous navigation. Inertial sensors can determine the motion of a body with respect to an inertial frame of reference. Traditionally, inertial systems are bulky, expensive and controlled by government regulations. Micro-electro mechanical systems (MEMS) inertial sensors are compact, small, inexpensive and most importantly, not controlled by governmental agencies due to their large error characteristics. Consequently, these sensors are the perfect candidate for integrated civilian navigation applications with GPS. However, these sensors need to be calibrated to remove the major part of the deterministic sensor errors before they can be used to accurately and reliably bridge GPS signal gaps. A new multi-position calibration method was designed for MEMS of high to medium quality. The method does not require special aligned mounting and has been adapted to compensate for the primary sensor errors, including the important scale factor and non-orthogonality errors of the gyroscopes. A turntable was used to provide a strong rotation rate signal as reference for the estimation of these errors. Two different quality MEMS IMUs were tested in the study. The calibration results were first compared directly to those from traditional calibration methods, e.g. six-position and rate test. Then the calibrated parameters were applied in three datasets of GPS/INS field tests to evaluate their accuracy indirectly by comparing the position drifts during short-term GPS signal outages.

Navigation involves the integration of methodologies and systems for estimating the time varying position and attitude of moving objects. Inertial Navigation Systems (INS) and the Global Positioning System (GPS) are among the most widely used navigation systems. The use of cost effective MEMS based inertial sensors has made GPS/INS integrated navigation systems more affordable. However MEMS sensors suffer from various errors that have to be calibrated and compensated to get acceptable navigation results. Moreover the performance characteristics of these sensors are highly dependent on the environmental conditions such as temperature variations. Hence there is a need for the development of accurate, reliable and efficient thermal models to reduce the effect of these errors that can potentially degrade the system performance. In this paper, the Allan variance method is used to characterize the noise in the MEMS sensors. A six-position calibration method is applied to estimate the deterministic sensor errors such as bias, scale factor, and non-orthogonality. An efficient thermal variation model is proposed and the effectiveness of the proposed calibration methods is investigated through a kinematic van test using integrated GPS and MEMS-based inertial measurement unit (IMU).

Patients with orocutaneous fistulas suffer from discomfort in terms of facial esthetics, food spill over and lack of psychological confidence to present them socially. Prosthetic camouflaging of facial defects and use of silicone maxillofacial material are the alternatives to the surgical retreatment. Silicone elastomers provide more options to clinician for customization of the facial prosthesis which is simple, esthetically good when coupled with bio magnets for retention.

articles epidemiology several identified from the literature (21-23). These protocols varied by anatomical site, posture, respiratory phase, and time since last meal. Methods and Procedures study design and settingA cross-sectional study was conducted from September 2005 to April 2006 at the All India Institute of Medical Sciences, New Delhi, a tertiary care hospital in North India. study populationHealthy volunteers (N = 123; males = 48, females = 75), mostly residents of New Delhi, of age >16 years were recruited by using local posters and advertisements. We excluded subjects with any systemic illness, pregnancy, ascites, intestinal obstruction tumor, or any other abdominal pathology. Anthropometric measurements were done after an overnight fast at the Metabolic Research Center. Appropriate informed consent was given by all volunteers before participation.The study protocol was approved by institutional review board on human research. Also, we certify that all applicable institutional regulations concerning the ethical conduct of research with human volunteers were followed during this research. anthropometric measurementsParticipants relaxed for 15 min before the measurements were taken. Body weight (to nearest 0.1 kg) and height (to nearest 0.01 m) were measured while subjects were dressed in light clothing and stood barefoot, erect with eyes directed straight ahead. Hip circumference (measured at the largest posterior extension of the buttocks) and WC were measured using a heavy-duty inelastic tape, kept in contact with skin without pressing it. WC measurements (to the nearest 0.001 m) varying by anatomical site, phases of respiration, and time since last meal were recorded. Special attention was given to keep the tape perpendicular to the long axis of the subject's body with the help of another observer. Volunteers were asked to eat a routine meal and then report back within 10 min for postmeal measures. WC was measured at two anatomical locations as follows: suprailiac (just lateral and above the iliac crest) in midaxillary line (according to NIH protocol (20)) and midabdomen (midpoint between subcostal and suprailiac landmarks) (according to World Health Organization (WHO) protocol (1)). Normal posture was defined as standing barefoot in a comfortable position with eyes directed straight ahead, while erect posture refers to standing barefoot on both feet with heels, buttocks, and occiput in contact with a straight wall; both arms hanging loosely by the side of body; and eyes directed straight ahead. Normal breathing was defined as breathing at a regular pace with tidal volume, and the measure was taken irrespective of the respiratory phase. Other phases of respiration, like normal end-expiration and end-inspiration, were demonstrated to the subjects and defined as described in Table 1. Similarly, forced end-inspiration and end-expiration were demonstrated and WC measured while the subjected inhaled to maximum lung capacity and then exhaled as hard and as completely as possible.Two repeat measurements of ...

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