How to Earn Money with an EMI Problem: Static Energy Meters Running Backwards

The increased use of non-linear appliances in households has resulted in several conducted electromagnetic interference issues, such as misreadings of static energy meters used for billing purposes of the households' energy consumption. In this paper a case is presented where a static energy meter indicates a power generation, while power is actually being consumed. A perceived power generation of more than 430 W is measured by a static energy meter installed in a household when a television with a commercial off the shelf remote controlled switch with dimming functionalities consumed 21 W. The same situation is reproduced in a controlled lab environment, to eliminate possible influences of other appliances in the grid, which confirmed the on-site results. The current waveforms causing this supposed generation of power are investigated and it is observed that the phase firing angle of the current pulse drawn by the load in combination with the commercial off the shelf remote controlled switch affects the metering errors and determines whether the errors indicate a false generation, a too high consumption of power, or no error at all. A combination of the household equipment and a basic unloaded switched mode power supply in conjunction with two remote controlled switches resulted in a perceived power generation of more than 600 W. Having these loads connected for the entire day would counteract the total consumption of an average household and could even "generate" energy, and thus generate money for the consumer

Femoral revision surgery with impaction bone grafting

The purpose of this prospective study was to evaluate the long-term clinical and radiological outcomes of revision of the femoral component of a total hip replacement using impaction bone grafting. Femoral revision with an impacted allograft was performed on 29 patients (31 hips). In all, 21 hips (68%) had grade III or IV femoral defects according to the Endo-Klinik classification. A total of 11 patients (12 hips) died before the ten-year follow-up period. Of the remaining patients, 18 patients (19 hips) were followed for 10 to 15 years; three further patients died during this time. None of the 31 stems underwent further revision of their stem. However, four stems showed extensive subsidence (> 15 mm). One of these patients had a femoral fracture that required fixation. Three other patients had a femoral fracture, two of which required fixation and the other was treated conservatively. Patients with a femoral fracture and/or severe subsidence had significantly more grade IV defects (six of seven hips; p = 0.004). One patient needed a closed reduction for dislocation. Impaction allografting in revision hip surgery gives good long-term results for femora with grades I

MRI Assessment of Muscle Damage After the Posterolateral Versus Direct Anterior Approach for THA (Polada Trial). A Randomized Controlled Trial

BACKGROUND: There is controversy in literature whether the direct anterior approach (DAA) results in less muscle damage compared with the posterolateral approach (PLA) for total hip arthroplasty. The aim of this randomized controlled trial was to assess muscle damage between these two approaches. METHODS: Forty-six patients were included. Muscle atrophy, determined with the Goutallier classification, and muscle surface of twelve muscles were analyzed on magnetic resonance imaging images made preoperatively and one year postoperatively. Differences in component placement after DAA or PLA were assessed on radiographs. Harris hip scores and Hip disability and Osteoarthritis and Outcome Score were used as functional outcomes. RESULTS: External rotator musculature was damaged in both approaches. After PLA, the obturator muscles showed significantly more atrophy and a decrease in muscle surface. After DAA, the tensor fascia latae showed an increased muscle atrophy and the psoas muscle showed a decreased muscle surface. An increase in muscle surface was seen for the rectus femoris, sartorius, and quadratus femoris after both approaches. The muscle surface of the gluteus medius and iliacus was also increased after PLA. No difference in muscle atrophy was found between the approaches for these muscles. The inclination angle of the cup in PLA was significantly higher. No differences were found in functional outcomes. CONCLUSION: Different muscle groups were affected in the two approaches. After PLA, the external rotators were more affected, whereas the tensor fascia latae and psoas muscles were more affected after DAA

The push-through total femoral prosthesis offers a functional alternative to total femoral replacement:a case series

PURPOSE: Oncologic resections or complications of segmental femoral prostheses can result in severe bone loss of the femur for which a total femoral prosthesis (TFP) is required. This study assesses whether the loss of stability and function caused by the loss of muscle attachments can be improved by using a push-through total femoral endoprosthesis (PTTF), because it saves parts of the femur and its muscle attachments. METHODS: In this retrospective case series, ten patients aged 25-77 (mean 54) who received a PTTF between 2005 and 2014 were included for baseline, complications and survival analysis with a mean follow-up of 5.3 (1.1-9.6) years. Functional outcome was assessed in six patients using the Musculoskeletal Tumor Society (MSTS) score, WHO performance scale, Toronto Extremity Salvage Score (TESS), SF36, EQ-5D, NRS pain score, fatigue score and satisfaction score. RESULTS: The mean MSTS score was 64% (23-93%). Five patients had a WHO performance scale of 1, one patient of 3. Mean TESS was 69% (13-90%). SF36 was most notably limited by physical functioning (mean 48), vitality (68) and general health (67). NRS score was 1.9, 1.8 and 8.3 for pain, fatigue and satisfaction, respectively. There were four failures: two infections (one resulting in amputation and one in a minor revision) and two mechanical failures (which required one revision to a TFP and one minor revision). Patient survival was 100%, limb survival 90%, and prosthesis survival 80%. CONCLUSION: The push-through total femoral endoprosthesis allows preservation of muscle attachments and offers a good alternative to total femoral prostheses

Estimation of static energy meter interference in waveforms obtained in on-site scenarios

© 2022 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Static energy meters have shown errors beyond the standards due to conducted electromagnetic interference of pulsed currents. This was observed in several case studies and confirmed by laboratory experiments, which showed errors up to 2675%. The extent of this interference case is unknown, because there is limited information about the waveforms occurring in the real on-site scenarios. This article aims to detect critical waveforms in on-site surveyed data that have similar characteristics as the pulses that resulted in metering errors. The time-domain parameters of the laboratory experiments that show static energy meter interference are compared to the on-site waveform data using an interpolation based on an inverse weighting distance function. Using this approach, the waveform characteristics are compared, and an error is estimated. This approach was satisfactorily validated using data from validation experiments that shows a correct estimation of the actual error according to the permissible limits for energy metering for all validation indices. The performed on-site surveys show the existence of nonlinear waveforms. During the survey of three sites for ten days, 19 531 waveforms were captured, of which 14 487 indicate large nonlinearities and 379 are estimated to produce metering errors up to 925%.Peer ReviewedPostprint (published version