Fleet's Geode: A Breakthrough Sensor for Real-Time Ambient Seismic Noise Tomography over DtS-IoT.

As most of the outcropping and shallow mineral deposits have been found, new technology is imperative to finding the hidden critical mineral deposits required to transition to renewable energy. One such new technique, called ambient seismic noise tomography, has shown promise in recent years as a low-cost, low environmental impact method that can image under cover and at depth. Wireless and compact nodal seismic technology has been instrumental to enable industry applications of ambient noise tomography, but these devices are designed for the active seismic reflection method and do not have the required sensitivity at low frequencies for ambient noise tomography, and real-time data transmission in remote locations requires significant infrastructure to be installed. In this paper, we show the development and testing of the Geode-a real-time seismic node purpose-built by Fleet Space Technologies for ambient seismic noise tomography on exploration scales. We discuss the key differences between current nodal technology and the Geode and show results of a field trial where the performance of the Geode is compared with a commercially popular nodal geophone. The use of a 2 Hz high sensitivity geophone and low noise digitiser results in an instrument noise floor that is more than 30 dB lower below 5 Hz than nodes that are commonly used in the industry. The increased sensitivity results in signal-to-noise ratios in the cross-correlation functions in the field trial that are more than double that of commercially available nodal geophone at low frequencies. When considering the full bandwidth of retrievable correlations in our study, using the Geode would reduce the required recording time from 75 h to 32 h to achieve an average signal-to-noise ratio in the cross-correlation functions of 10. We also discuss the integration of a real-time direct-to-satellite Internet of Things (DtS-IoT) modem in the Geode, which, together with edge processing of seismic data directly on the Geode, enables us to image the subsurface in real-time. During the field trial, the Geodes successfully transmitted more than 90% of the available preprocessed data packets. The Geode is compact enough so that several devices can be carried and installed by one field technician, whilst the array of stations do not require a base station to transmit data to the cloud for further processing. We believe this is the future of passive seismic surveys and will result in faster and more dynamic seismic imaging capabilities analogous to the medical imaging community, increasing the pace at which new mineral deposits are discovered.

Acetabular Subchondral Bone Decortication and Its Role in the Outcome of Cemented Total Hip Replacement in Young Patients / 대한고관절학회지

PURPOSE: Long-term fixation of cemented acetabular components can be problematic in younger active patients. Our technique is put forward to improve outcomes and maximize implant survivorship in this particular patient population. MATERIALS AND METHODS: We report on a cohort of young adult patients (less than 55 years old) with cemented total hip replacement (THR) using a novel technique in preparing and cementing the acetabulum with a minimum follow-up of 10 years (mean follow-up, 14 years). Retrospectively collected data on clinical and radiological outcomes were reviewed. RESULTS: Sixty-five THRs were performed with the minimum study follow-up period. Average age for patients was 44 years old (range, 19–55 years). The mean Hip Disability and Osteoarthritis Outcome Score for patients at final appointment was 92.7. Radiographs taken at an average of 14 years after operation showed 63 of 65 hips showed no evidence of any radiological loosening. Cup survivorship was 100% at the end of the study period. CONCLUSION: Our technique of preparing the acetabulum in combination with cement fixation is reproducible with excellent results in a cohort of patients prone to early aseptic loosening of the acetabular component.