In this paper, an extended impedance-based fault-location formulation for generalized distribution systems is presented. The majority of distribution feeders are characterized by having several ...laterals, nonsymmetrical lines, highly unbalanced operation, and time-varying loads. These characteristics compromise traditional fault-location methods performance. The proposed method uses only local voltages and currents as input data. The current load profile is obtained through these measurements. The formulation considers load variation effects and different fault types. Results are obtained from numerical simulations by using a real distribution system from the Electrical Energy Distribution State Company of Rio Grande do Sul (CEEE-D), Southern Brazil. Comparative results show the technique robustness with respect to fault type and traditional fault-location problems, such as fault distance, resistance, inception angle, and load variation. The formulation was implemented as embedded software and is currently used at CEEE-D's distribution operation center.
Power distribution automation and control are important tools in the current restructured electricity markets. Unfortunately, due to its stochastic nature, distribution systems faults are hardly ...avoidable. This paper proposes a novel fault diagnosis scheme for power distribution systems, composed by three different processes: fault detection and classification, fault location, and fault section determination. The fault detection and classification technique is wavelet based. The fault-location technique is impedance based and uses local voltage and current fundamental phasors. The fault section determination method is artificial neural network based and uses the local current and voltage signals to estimate the faulted section. The proposed hybrid scheme was validated through Alternate Transient Program/Electromagnetic Transients Program simulations and was implemented as embedded software. It is currently used as a fault diagnosis tool in a Southern Brazilian power distribution company.
The intra-articular injury most often associated with a chronic anterior cruciate ligament tear involves the posterior horn of the medial meniscus. A specific type of medial meniscal injury, called a ...ramp lesion, has received greater attention for identification and treatment because of its considerable incidence and diagnostic difficulty. Based on their location, these lesions may be arthroscopically “hidden” during traditional anterior visualization. The purpose of the present Technical Note is to describe the Recife maneuver. This maneuver diagnoses injuries to the posterior horn of the medial meniscus using additional arthroscopic management through a standard portal. The Recife maneuver is performed with the patient in the supine position. A 30° arthroscope is inserted through the anterolateral portal, and the posteromedial compartment is accessed according to the transnotch view (modified Gillquist view). In the proposed maneuver, with the knee in 30° of flexion, a valgus stress with internal rotation is performed, followed by palpation of the popliteal region and digital pressure on the joint interline. This maneuver allows a greater visualization of the posterior compartment, allowing the diagnostic evaluation of the integrity between the meniscus and the capsule, in a safer way, being able to identify ramp tears without the need to create a posteromedial portal. We recommend that the addition of the diagnostic visualization step of the posteromedial compartment as described by the Recife maneuver be performed to assess the meniscal status in routine anterior cruciate ligament reconstruction.
Display omitted
Underground distribution systems are normally exposed to permanent faults, due to specific construction characteristics. In these systems, visual inspection cannot be performed. In order to enhance ...service restoration, accurate fault location techniques must be applied. This paper describes an extended impedance-based fault location algorithm for underground distribution systems. The formulation is developed on phase frame and calculates the apparent impedance using only local voltage and current data. The technique also provides an iterative algorithm to compensate the typical capacitive component current of underground cables. Test results are obtained from numerical simulations using a real underground distribution feeder data from the Electrical Energy Distribution State Company of Rio Grande do Sul (CEEE-D), southern Brazil. Comparative results show the techniques accuracy and robustness in respect to fault type, distance and resistance.
The objective of this study was to evaluate the dynamic balance of the injured and uninjured limb before and after the anterior cruciate ligament (ACL) reconstruction and compare with the control ...group.
Prospective longitudinal.
Biomechanics laboratory.
Participants are 24 males (mean age, 27.5 years) with unilateral ACL injury (ACLG) and 24 male healthy volunteers (CG).
The modified star excursion balance test (SEBT) and isokinetic knee extensor and flexor strength were applied in the ACLG preoperatively and after surgery. The dominant limb of CG was evaluated at a single time.
There was no difference between the injured and the uninjured limb of the ACLG (P > 0.05) before and after surgery. Preoperatively, both ACLG limbs had a significantly lower reach distance in posteromedial (PM) and posterolateral (PL) directions and in composite reach (CR) score compared to the control group (P < 0.001). Postoperatively, no significant differences were found between ACLG and CG (P > 0.05). There was a positive correlation between preoperative PL (0.59) and CR (0.51), postoperative PM (0.36), PL (0.36) and CR (0.46) with flexor strength at 12 months after surgery.
Patients with ACL injury presented a worse performance in the SEBT in the preoperative period compared to the control group. After ligament reconstruction, the performance in the SEBT became equivalent to that of the control group. The strong correlation between flexor strength and posterior directions of the injured limb demonstrates the importance of the knee flexor muscles in the neuromuscular control of patients submitted to ACL reconstruction.
Fault resistance is a critical variable in distance relaying. If not considered due to underreaching phenomenon, it may cause the misoperation of ground distance relays for internal faults. Still, as ...a consequence of the overreaching phenomenon, the unbalanced nature of loads and asymmetry of lines can affect the distance protection operation efficiency. Mainly due to these aspects, there is low precision in protection zone limits of ground distance relays. In this paper, a new algorithm is proposed to increase the precision of these limits, improving efficiency in the distance protection process. The proposed method is based in phase coordinates and uses a fault resistance estimate to develop the trip decision procedure. The results show that the algorithm is suitable for online applications, and that it has an independent performance from the fault resistance magnitude, the fault location, and the line asymmetry.
Background:
This article describes a standardized, minimally invasive approach for harvesting the quadriceps tendon through a 2 to 3 cm transverse skin incision, presenting it as a viable option.
...Indications:
This procedure is indicated for patients undergoing anterior cruciate ligament (ACL), posterior cruciate ligament, medial collateral ligament, or lateral collateral ligament reconstruction surgery using soft tissue quadriceps grafts.
Technique Description:
A transverse incision is made on the anterior face of the knee, followed by a longitudinal incision of the central third of the rectus femoris. We perform the distal detachment of the patella of the same tendon. Then, the tendon is extracted using a closed stripper. The graft is prepared and folded on itself, resulting in a double graft.
Results:
Twenty patients, 16 male and 4 female with complete rupture of ACL, were submitted to an ACL reconstruction using the quadriceps soft tissue graft with minimally invasive harvesting technique. The results were satisfactory for all patients. All patients showed good evolution in the immediate and late postoperative period, with no cases of joint stiffness, wound dehiscence, and no infections.
Discussion/Conclusion:
We can conclude that harvesting the quadriceps tendon with a minimally invasive approach is a valid and reliable option for the treatment of ligament tears of the knee.
Patient Consent Disclosure Statement:
The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form.
Graphical Abstract
This is a visual representation of the abstract.
Abstract Objective We studied the microbiological profile of periprosthetic knee infections treated in a Brazilian tertiary hospital. Methods The study included all patients undergoing revision ...surgery for total knee arthroplasty (RTKA) between November 2019 and December 2021, with a diagnosis of periprosthetic infection confirmed per the 2018 International Consensus Meeting (ICM) criteria. Results Sixty-two patients had a periprosthetic joint infection (PJI) per the 2018 ICM criteria. Cultures were monomicrobial in 79% and polymicrobial in 21% of cases. The most frequent bacterium in microbiological tissue and synovial fluid cultures was Staphylococcus aureus, observed in 26% of PJI patients. Periprosthetic joint infection with negative cultures occurred in 23% of patients. Conclusion Our results show the following: i) a high prevalence of Staphylococcus as an etiological agent for knee PJI; ii) a high incidence of polymicrobial infections in early infections; iii) the occurrence of PJI with negative cultures in approximately one fourth of the subjects.
This letter presents an extension of an existing ground distance relay algorithm to include phase distance relays. The algorithm uses a fault resistance estimation process in the phase domain, ...improving efficiency in the distance protection process. The results show that the algorithm is suitable for online applications, and that it has an independent performance from the fault resistance magnitude, the fault location, and the line asymmetry.
► An extended bus impedance phase component fault analysis formulation is developed. ► A
R
F
estimate formulation is presented considering distribution system asymmetries. ► Fault resistance estimate ...is included in fault analysis formulation.
► R
F
estimates have some dependency to its value and are invariant to fault location. ► Fault analysis accuracy is independent to fault resistance and fault location.
Fault resistance is a critical component of electric power systems operation due to its stochastic nature. If not considered, this parameter may interfere in fault analysis studies. This paper presents an iterative fault analysis algorithm for unbalanced three-phase distribution systems that considers a fault resistance estimate. The proposed algorithm is composed by two sub-routines, namely the fault resistance and the bus impedance. The fault resistance sub-routine, based on local fault records, estimates the fault resistance. The bus impedance sub-routine, based on the previously estimated fault resistance, estimates the system voltages and currents. Numeric simulations on the IEEE 37-bus distribution system demonstrate the algorithm’s robustness and potential for offline applications, providing additional fault information to Distribution Operation Centers and enhancing the system restoration process.
