Optimal Repair Research Articles

PROSTHESIS REPAIR OF ORAL IMPLANTS BASED ON ARTIFICIAL INTELLIGENC`E FINITE ELEMENT ANALYSIS

Dentists often suggest dental implants to replace missing teeth; nevertheless, mechanical issues can develop with these implants, which could lead to prosthesis replacement or repairs. When investigating implant systems' mechanical characteristics and stress distribution, finite element analysis (FEA) is a popular computational tool. In biomechanical investigations, this strategy is widely used. However, traditional FEA methods can be tedious and require expert expertise for accurate simulation and translation of results. To automate and simplify the process of mending oral implant prostheses, the article suggests a new framework called AI-FEA. The three primary parts that make up the suggested AI-FEA framework are 1. An AI-powered model creation module that utilizes data from medical imaging to autonomously construct 3D finite element designs that are unique to each patient. Utilizing deep learning approaches, this module segments and reconstructs three-dimensional geometries from computed tomography (CT) or cone-beam CT data using material properties and boundary conditions. 2. A FEA solver that runs simulations to test the way the implant system handles different loads. This component uses state-of-the-art numerical methods to model the implant and bone interface and determine stress distributions. 3. An AI-based decision support system that takes all that data and recommends the best way to fix the prosthesis. Combining FEA findings with patient-specific variables, this decision support system uses machine learning algorithms educated on an extensive dataset of implant failure instances and repair results to provide the optimal repair strategy. For patients experiencing issues with oral implants, the suggested AI-FEA framework might mean huge time and skill savings in prosthesis repair planning, leading to better, more individualized care.

In Vitro Analysis of Shear Bond Strength in Repaired Cohesive and Adhesive Fractures of Conventional and DMLS Porcelain-fused-to-metal Crowns.

Porcelain-fused-to-metal (PFM) restorations are essential in fixed prosthodontics for their strength and esthetics, but are prone to fractures due to material disparities and stress factors. This study evaluates the shear bond strength (SBS) of two porcelain repair systems for cohesive and adhesive fractures in conventional PFM and direct metal laser-sintered (DMLS) restorations, addressing clinical repair needs. Thirty metal-ceramic discs were fabricated and divided into two main groups based on the fabrication method: Conventional casting and DMLS. Each group had three subgroups: Conventional casting (A: Control, B: Cohesive defect, C: Adhesive defect) and DMLS (D: Control, E: Cohesive defect, F: Adhesive defect), each with 5 specimens. Shear bond strength was measured using a Universal Testing Machine (UTM) at 0.5 mm/min. Data were analyzed with a one-way ANOVA (α = 0.05), and Tukey's post hoc test was used for significant differences. Student's t-tests compared SBS between control groups. A one-way ANOVA revealed significant differences in SBS among Conventional Casting subgroups (p < 0.001). Subgroup A (36.282 ± 1.692 MPa) had higher SBS than B (13.202 ± 1.336 MPa) and C (17.033 ± 1.634 MPa), with Tukey's test confirming significant differences (p < 0.001). For DMLS subgroups, subgroup D (37.768 ± 0.560 MPa) had higher SBS than E (22.381 ± 1.137 MPa) and F (13.245 ± 0.693 MPa), with Tukey's test showing significant differences (p < 0.001). No significant difference was found between subgroups A and D (p = 0.10). Subgroup E had a higher SBS than B (p < 0.001), and subgroup C had a higher SBS than F (p = 0.001). This study offers insights into the performance of two porcelain repair systems, aiding clinicians in selecting effective materials and techniques for PFM restoration repairs. Understanding the bond strength of these repair systems can enhance clinical outcomes by guiding the selection of optimal repair materials and techniques, improving the longevity and durability of fractured PFM restorations. How to cite this article: Irissan R, Mohan A, Augustine C, et al. In Vitro Analysis of Shear Bond Strength in Repaired Cohesive and Adhesive Fractures of Conventional and DMLS Porcelain-fused-to-metal Crowns. J Contemp Dent Pract 2024;25(8):726-731.

Hybrid Thoracic Endovascular Repair of a Large, Saccular Aortic Arch Aneurysm with Coil Embolization of the Left Subclavian Artery in a 31 Year Old Filipino Female with Takayasu Arteritis and Multiple Intracranial Aneurysms: A First in the Philippines

BACKGROUND: Takayasu Arteritis (TA) is a rare, primary large-vessel vasculitis frequently leading to stenosis and less commonly, aneurysm formation. Saccular aneurysms of the aortic arch in patients with TA are fatal, have rarely been reported and represent a significant technical challenge due to the difficult anatomical location and need for protection of the cerebral circulation. Concomitant intracerebral aneurysms in patients with TA are extremely uncommon and have mostly been documented in very few case reports in literature. CASE DISCUSSION: We present a case of a 31 year-old Filipino female with recurrent chest and neck pain radiating to the upper back. Computed tomographic (CT) angiography demonstrated a large saccular aortic arch aneurysm without branch stenosis. CTA of the cerebral circulation likewise demonstrated multiple, saccular, intra-cerebral aneurysms. She underwent hybrid thoracic arch repair with supra-aortic debranching via mini-sternotomy and proximal ligation of the left common carotid artery and staged endovascular aortic arch replacement with coil embolization of the ostial-to-proximal left subclavian artery segment. Post-operative aortogram showed optimal repair with thrombosed aneurysmal sac, optimal graft position, no endoleaks and preservation of cerebral circulation. Patient improved symptomatically post-procedure and remained symptom-free during follow-up after six months. Careful review of local literature suggests that this is the first Philippine TA case with a saccular aortic arch aneurysm successfully managed in this manner. CONCLUSION: Saccular aortic arch aneurysms in patients with Takayasu are unusual and presence of concomitant multiple cerebral saccular aneurysms have rarely been reported in literature. This case highlighted that hybrid endovascular arch repair in patients with TA is feasible, minimally invasive and effective. KEYWORDS: Takayasu arteritis, aortic arch aneurysm, cerebral aneurysm, hybrid endovascular arch repair, aortic de-branching

Progress in Dentin-Derived Bone Graft Materials: A New Xenogeneic Dentin-Derived Material with Retained Organic Component Allows for Broader and Easier Application.

The optimal repair of rigid mineralized tissues, such as bone, in cases of fracture, surgical resection, or prosthetic placement, is a complex process often necessitating the use of bone graft materials. Autogenous bone from the patient is generally the gold standard in terms of outcomes but also has disadvantages, which have resulted in extensive research in the field of tissue engineering to develop better and more convenient alternatives. In the dental field, several initiatives have demonstrated that the dentin material derived from extracted teeth produces excellent results in terms of repairing bone defects and supporting dental implants. Dentin is acellular and thus, in contrast to autogenous bone, cannot provide osteoblasts or other cellular elements to the grafted region, but it does contain growth and differentiation factors, and has other properties that make it an impressive material for bone repair. In this review, the beneficial properties of dentin and the ways it interacts with the host bone are described in the context of bone graft materials. Autogenous tooth material has limitations, particularly in terms of the need for tooth extraction and the limited amount available, which currently restrict its use to particular dental procedures. The development of a xenograft dentin-derived material, which retains the properties of autogenous dentin, is described. Such a material could potentially enable the use of dentin-derived material more widely, particularly in orthopedic indications where its properties may be advantageous.

Vascularised and Non-Vascularised Adipofascial Flap Applications in Tissue Trauma with Tendon Injury, Flap Viability and Tendon Healing a Hystological and Scintigraphical Rat Model Study.

Background and Objectives: Complex wounds in the hand and distal lower extremities pose challenges in reconstructive surgery, often involving critical structures like tendons. Tendon injuries, prevalent in such wounds, necessitate optimal repair methods for functional recovery. This study investigates the impact of vascularised and nonvascularised adipofascial tissue on tendon repair, focusing on early healing stages, mobilisation, and scintigraphic evaluation of flap vascularity. Materials and Methods: Wistar Albino rats were divided into groups undergoing primary tendon repair, vascularised adipofascial flap application, or nonvascularised flap application. Scintigraphic evaluation and histopathological assessment were performed to analyse healing processes. Results: Pedicle-free flaps support healing in tendon injuries without negatively affecting medium-term outcomes. Vascularised flaps exhibit faster healing. The scintigraphic analysis showed that the static measurements of the late phase were statistically significantly higher in the group with the non-vascularised adipofascial flap (p = 0.038). The mean perfusion reserve was higher in the vascularised pedicled adipofascial flap group than the non-vascularised adipofascial flap group. Scintigraphic analysis highlights the viability of pedicle-free flaps. Conclusions: Pedicle-free adipofascial flaps support the healing of the tendon without complicating the results, while vascularised flaps show accelerated healing. These findings provide valuable insights into optimising tendon repair strategies using adipofascial flaps, with implications for enhancing functional recovery in complex wounds.

Biomechanical Comparison of Three Modified Kessler Techniques for Flexor Tendon Repair: Implications in Surgical Practice and Early Active Mobilization.

Objective: Managing flexor tendon injuries surgically remains challenging due to the ongoing debate over the most effective suture technique and materials. An optimal repair must be technically feasible while providing enough strength to allow for early active mobilization during the post-operative phase. This study aimed to assess the biomechanical properties of three modified Kessler repair techniques using two different suture materials: a conventional two-strand and a modified four-strand Kirchmayr-Kessler repair using 3-0 Prolene® (2s-KK-P and 4s-KK-P respectively), and a four-strand Kessler-Tsuge repair using 4-0 FiberLoop® (4s-KT-FL). Methods: Human flexor digitorum profundus (FDP) tendons were retrieved from Thiel-embalmed prosections. For each tendon, a full-thickness cross-sectional incision was created, and the ends were reattached using either a 2s-KK-P (n = 30), a 4s-KK-P (n = 30), or a 4s-KT-FL repair (n = 30). The repaired tendons were tested using either a quasi-static (n = 45) or cyclic testing protocol (n = 45). Maximum force (Fmax), 2 mm gap force (F2mm), and primary failure modes were recorded. Results: In both quasi-static and cyclic testing groups, tendons repaired using the 4s-KT-FL approach exhibited higher Fmax and F2mm values compared to the 2s-KK-P or 4s-KK-P repairs. Fmax was significantly higher with a 4s-KK-P versus 2s-KK-P repair, but there was no significant difference in F2mm. Suture pull-out was the main failure mode for the 4s-KT-FL repair, while suture breakage was the primary failure mode in 2s- and 4s-KK-P repairs. Conclusions: FDP tendons repaired using the 4s-KT-FL approach demonstrated superior biomechanical performance compared to 2s- and 4s-KK-P repairs, suggesting that the 4s-KT-FL tendon repair could potentially reduce the risk of gapping or re-rupture during early active mobilization.

Pythia: Non-random DNA repair allows predictable CRISPR/Cas9 integration and gene editing.

CRISPR-based genome engineering holds enormous promise for basic science and therapeutic applications. Integrating and editing DNA sequences is still challenging in many cellular contexts, largely due to insufficient control of the repair process. We find that repair at the genome-cargo interface is predictable by deep-learning models and adheres to sequence context specific rules. Based on in silico predictions, we devised a strategy of triplet base-pair repeat repair arms that correspond to microhomologies at double-strand breaks (trimologies), which facilitated integration of large cargo (>2 kb) and protected the targeted locus and transgene from excessive damage. Successful integrations occurred in >30 loci in human cells and in in vivo models. Germline transmissible transgene integration in Xenopus, and endogenous tagging of tubulin in adult mice brains demonstrated integration during early embryonic cleavage and in non-dividing differentiated cells. Further, optimal repair arms for single- or double nucleotide edits were predictable, and facilitated small edits in vitro and in vivo using oligonucleotide templates. We provide a design-tool (Pythia, pythia-editing.org) to optimize custom integration, tagging or editing strategies. Pythia will facilitate genomic integration and editing for experimental and therapeutic purposes for a wider range of target cell types and applications.

Biomechanical analysis of cadaver rabbit Achilles tendons after full transection and suture: Comparison of U-Tang 4-strand with the cross-locked version of U-Tang 4-strand suture technique

IntroductionTendon injures rank as the second most common hand injuries, and unsatisfactory repair can significantly impact a patient's everyday life. Over the years, various suture techniques have been studied in the pursuit of finding the optimal repair method. The ideal tendon repair should achieve maximum strength, while being easy to perform and minimizing tissue trauma. This study aims to compare the mechanical properties of the cross-locked U-Tang 4-strand suture to its unmodified version, the U-Tang 4-strand suture, to assess which technique offers greater repair strength. MethodsSixteen Achilles tendons from New Zealand White rabbits were randomly assigned to one of two suture technique groups; an original U-Tang 4-strand suture or a cross-locked U-Tang 4-strand suture, both performed using a 4-0 Supramid thread. The specimens were tested in uniaxial tension after a preconditioning phase. Cross-sectional area, load until failure, gap formation, stiffness, elastic modulus, and failure stress were determined. ResultsThe standard U-Tang 4-strand suture withstood a maximum force of 25.48 ± 6.06 N, while the cross-locked version endured 33.90 ± 6.09 N. This indicates that the modified version demonstrated significantly greater strength (p = 0.021). The elastic modulus of the cross-locked U-Tang 4-strand suture (0.02 ± 0.003 MPa) was significantly higher than that of the original version (0.01 ± 0.006 MPa) (p = 0.028). No significant differences were observed regarding the cross-sectional area, load at 2 mm gap formation, stiffness and failure stress. ConclusionEmploying the cross-locked U-Tang 4-strand suture results in a significantly greater maximum force and elastic modulus compared to the original U-Tang 4-strand suture, utilizing the same thread and number of strands and knots. Therefore, the cross-locking version provides an alternative for achieving more stable initial repair strength.

Toward Lower Repair Bandwidth and Optimal Repair Complexity of Piggybacking Codes With Small Sub-Packetization

Toward Lower Repair Bandwidth and Optimal Repair Complexity of Piggybacking Codes With Small Sub-Packetization

Open suture repair versus PermacolTM mesh repair of small ventral hernias in patients with end-stage kidney disease.

Ventral hernia is a common surgical problem among patients with end-stage kidney disease (ESKD), while the optimal repair technique for small ventral hernias is controversial. This study aimed to compare the outcomes of open suture repair versus biological mesh repair of small ventral hernias with defect size ≤2 cm in ESKD patients. Data from consecutive ESKD patients who underwent elective ventral hernia repair with defect size ≤2 cm at a single institution from January 2012 to January 2022 were retrospectively reviewed. Outcomes of open suture repair were compared to PermacolTM mesh repair. The primary outcome was recurrence rate. Secondary outcomes included post-operative complications, peri-operative and post-operative dialysis regimen. Forty-seven ventral hernia repairs were included, with 20 being suture repairs and 27 being PermacolTM mesh repairs. Median age at hernia repair was 60 (range 32-81) years old. Pre-operatively, 42 patients (89.4%) were on peritoneal dialysis (PD). Paraumbilical hernia (59.6%) was most common. Median hernia defect size was 15 mm (range 2-20 mm). Upon median follow-up of 56 (range 9-119) months, more patients in the suture repair group developed recurrence (30% vs. 0%, p = 0.004). Median time to recurrence was 10 (range 5-16) months. There was no wound or mesh infection. The majority of patients underwent intermittent PD peri-operatively and were able to resume on PD in the long run. Ventral hernia repair is indicated in ESKD patients even for small defects; repair with PermacolTM mesh was associated with a lower recurrence rate when compared to suture repair and post-operative morbidity was low.

A practical path planning method for optimal repair paths between multiple small-size defects

PurposeThis study aims to solve the problem of repair path planning between multiple small-size defects in the field of additive manufacturing (AM) repair by using Python-based ant colony algorithm (ACO). The optimal parameter combination scheme is obtained by discussing the influencing factors of parameters in the ACO.Design/methodology/approachThe effects of the information heuristic factor α, the expected heuristic factor ß and the pheromone volatile factor ρ on the simulation results were investigated by designing a three-factor and three-level orthogonal experiment. The fast convergence of ACO in finding the optimal solution of multiple small-size defect repair path problem is proved by comparing the simulation results with those of genetic algorithm (GA) on the same data set.FindingsThe ACO can effectively solve the repair path planning problem between multiple small-size defects by optimizing the parameters. In the case of 50 defect locations, the simulation results of the ACO with optimized parameters are 159.8 iterations and 3,688 average path lengths, while the GA has 4,027.2 average path lengths under the same data set and the same number of iterations, and by comparison, it is proved that the ACO can find the optimal solution quickly in the small-size defects repair path planning problem, which greatly improves the efficiency of defect repair.Originality/valueThe parameter-optimized ACO can be quickly applied to the planning problem of repair paths between multiple small-size defects in the field of AM repair, which can better improve the defect repair efficiency and reduce the waste of resources.

Impact of permanent pacemaker for iatrogenic atrioventricular block on outcomes after congenital heart surgery

ObjectiveThe need for permanent pacemaker (PPM) for iatrogenic atrioventricular block (AVB) after congenital heart surgery is approximately 1%. We aimed to evaluate the long-term outcomes of patients with PPM for iatrogenic AVB and compare them with patients with an optimal repair (trivial/no residual) Residual Lesion Score (RLS) Class 1 repair without PPM need. MethodsWe reviewed 183 patients discharged with PPM for iatrogenic AVB from 2011 to 2022. Patients who survived to discharge with >30 days of follow-up were matched 1:1 with a cohort of patients categorized as RLS Class 1 on the basis of fundamental diagnosis and primary procedure. ResultsMedian age at PPM placement was 1.4 years (interquartile range, 4.3 months to 3.9 years). The cumulative incidence of moderate or greater ventricular dysfunction at 1 year and 5 years was 11% and 18% in patients with PPM, respectively, compared with 3% and 7% in patients categorized as RLS Class 1 (subdistribution hazard ratio, 2.6; 95% confidence interval, 1.2-6.1; P = .022). Independently, patients with PPM with hypoplastic left heart syndrome (P = .027) and who had undergone Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery Mortality Category 5 procedures (P = .033) were at greater risk of ventricular dysfunction. Transplant-free survival at 1 year and 5 years was 94% and 89% in patients with PPM, respectively, compared with 98% and 97% in patients categorized as RLS Class 1 (P = .044). In addition, patients with PPM with palliated circulation had significantly lower transplant-free survival (P < .001). ConclusionsCompared with patients with an optimal repair without PPM, patients with PPM for iatrogenic AVB are at greater risk of developing moderate or greater ventricular dysfunction and have lower transplant-free survival.

RLclean: An unsupervised integrated data cleaning framework based on deep reinforcement learning

Data cleaning, a prerequisite to subsequent data analysis, has always been the focus of data science research. Datasets with errors can severely detract from the quality of downstream analytical results. Unfortunately, despite the proliferation of various data cleaning methods, it remains a time-consuming problem and frequently entails considerable labor expenses. In reality, errors are often heterogeneous and require different solutions. As a result, stand-alone methods often inadequate for addressing dirty data with multiple types of errors, while studies have demonstrated that combining such methods always require human intervention and the result remains unsatisfactory.In this paper, we propose an unsupervised integrated data cleaning framework, namely RLclean. Based on deep reinforcement learning, RLclean takes advantages of multiple data cleaning techniques, enabling it to effectively clean multiple types of errors and achieve satisfactory results. Additionally, it eliminates the need for costly human involvement, as the cleaning strategy is learned by data-driven, which further allows the framework to self-adapt to diverse domains. RLclean mainly consists of two parts: (i) an integrated error detection model that unites multiple techniques to detect different types of errors from multiple views; and (ii) an integrated data repair model that learns the optimal repair operations and repairs dirty data in an unsupervised manner. Extensive experiments on benchmark datasets have demonstrated the superiority of RLclean over state-of-the-art methods.

Stochastic modeling and optimization of discrete-time cold standby repairable systems with unreliable repair facility and retrial mechanism

This study develops novel reliability models for discrete-time cold standby repairable systems with unreliable repair facility and retrial mechanism. In view of the situation that the state of some engineering systems cannot be continuously monitored, discrete distribution is used to describe the distribution of random variables involved in this paper. For the case that multiple events can occur simultaneously in the discrete-time system model, the priority order of multiple events occurring simultaneously is defined. Two different models are proposed based on two types of priority rules. The retrial mechanism of the components is considered in the case that the failure information of the system components cannot be successfully transmitted to the repair facility. The preventive maintenance (PM) and repair after the breakdown of the repair facility are considered. The key reliability indices are derived by using the iterative algorithm of the difference equation and the generative function method. The algorithms for calculating system state probability, key reliability indices and cost–benefit ratio (CBR) are designed. To demonstrate the impact of each parameter on the system reliability indices, numerical results are provided. The optimal repair rate configuration scheme is chosen using the Particle Swarm Optimization (PSO) algorithm to achieve the lowest possible CBR. The impact of the system model with or without PM on stationary availability and CBR is shown. In addition, the impact of the number of system components on a series of system performance indices is analyzed, and the optimal number of components of the system corresponding to the minimum value of CBR is obtained.

A Retrospective Hospital-Based Study to Evaluate the Results of Extensor Tendon Injuries of the Hand, Wrist, and Forearm Treated Surgically in a Tertiary Care Hospital.

Introduction The important factors determining the treatment of extensor tendon injuries include the anatomical zone, type of injury, mode of injury, chronicity, and pathology of the adjacent tissues (principally the skin, bone, and joints). Very few studies have collectively studied the outcomes of all the wrist, forearm, and hand extensors.Hence, the major aim of this study was to evaluate the resultsof extensor tendon injuries of the hand, wrist, and forearm that were treated surgically. Methodology This was a hospital-based retrospective study done in a tertiary teaching hospital in South India. A total of 30 patients (23 males, seven females) were included in the study.All the cases of extended tendon injuries of the wrist, hand, and forearm were treated surgically, and those willing to participate were included in the study afterobtaining institutional ethics committee approval. Results The study included 30 patients, predominantly males (76.66%). The majority were aged 31-40 years (33.33%). Occupational injuries were the most common cause (36.66%), followed by road traffic accidents (RTAs) and glass cuts (26.66%). Right-sided injuries were more frequent (56.66%), with zone VI being the most affected (43.33%). Extensor digitorum communis was the most injured tendon (40%). Various suture techniques were used, including horizontal mattress and modified Kessler's. Complications occurred in four patients, including hematoma and surgical site infections. Functional outcomes, assessed by Miller's Criteria, indicated extension lag and flexion loss as key recovery measures. Conclusion Hand function is essential for daily life activities, and optimal repair and reconstruction of extensor tendon injuries are crucial to avoid functional disability. While the present study demonstrated positive outcomes, further research with larger sample sizes and more rigorous designs is needed to validate these findings and improve treatment strategies for hand injuries.

Study on the Mechanical Properties of Crack Mortar Repaired by Enzyme-Induced Calcium Carbonate Precipitation (EICP).

As an emerging repair method, the enzyme-induced calcium carbonate precipitation (EICP) technique has the advantages of being highly economical, eco-friendly, and durable. The optimal repair conditions were obtained by taking cement mortar as the research object, adding two types of filling medium, using three EICP-based repair methods to repair the cement mortar with different crack widths, and combining ultrasonic testing and strength testing to evaluate the mechanical properties and repair effects of the repair mortar. The microscopic structure of the mortar was established using mesoscopic and microscopic tests (XRD, SEM, and EDS), thereby revealing the mechanism of repair based on EICP. The test results show that, when quartz sand is used as the repair medium, more calcium carbonate adheres to the cross-section of test samples, and it has a better repair effect. Moreover, the repair effect of the injection method is significantly higher than those of the perfusion and immersion methods, and the ultrasonic wave transit time decreases by 1.22% on average. Based on the combination of quartz sand and EICP repair methods, the calcium carbonate precipitated among the sand granules contributes to a binding effect that strengthens the cohesive force among the sand granules.

Crack-healing ability of concrete enhanced by aerobic-anaerobic bacteria and fibers

In this study, the self-healing of cracks in four repair systems mixed by aerobic-anaerobic bacteria and fiber is studied. The results showed that specimens S-1, S-3, and S-4 demonstrate remarkable efficacy in achieving complete repair for the majority of cracks with widths of 0.6 mm or less within a healing period of 28 d. Conversely, cracks exceeding 0.45 mm in width in specimen S-2 present challenges in achieving complete restoration. The Water permeability experiments showed that the crack repair effect of the four groups of specimens was in the following order: S-4 > S-3 > S-1 > S-2. Notably, cracks with initial widths <0.4 mm exhibit a commendable secondary repair rate of approximately 90 %. Further analysis underscores the fiber-reinforced binary microbial mineralization repair system (S-4) as yielding optimal repair outcomes, significantly enhancing water seepage resistance post-repair. This comprehensive investigation underscores the potential of our proposed repair systems to effectively crack-healing.

Recovery Scheduling of Road Networks Considering Day-to-Day Flow Evolution

Natural disasters can lead to substantial disruptions in road networks, making many critical links unusable. It is important to timely repair the damaged links as they allow transportation of emergency services, relief materials, and so forth, after disasters. Many existing studies that focus on optimal recovery of damaged links after disasters assume that only a single agency is available for repair. Moreover, most of the existing studies do not consider travel time on links to be a function of traffic flow passing through the links and assume that the traffic flow gets distributed based on user equilibrium each time a link is repaired. However, such a traffic distribution is unrealistic as it assumes that the traffic flow remains the same across all the days for which a link is repaired and the traffic distribution gets suddenly modified whenever a link is fully repaired. The goal of this paper is to address these gaps in the literature of disaster recovery. We study the problem of determining the optimal repair scheduling of damaged links to minimize the sum of the total system travel time over the repair duration given that multiple repair agencies are available for recovery. Also, we consider a day-to-day traffic flow evolution where the route choices of travelers depend on the travel conditions of the previous day. We formulate this problem as a mixed-integer non-linear program. We proposed two solution methodologies to solve the problem: a genetic algorithm and a greedy algorithm. We tested these methodologies under different settings.

Prediction of Distal Femoral and Posterior Articular Surfaces in Total Knee Arthroplasty With Severe Bone Defects Using Computed Tomography-Based Templating Software.

Introduction Optimal repair of the joint line (JL) in total knee arthroplasty (TKA) is critical for knee joint motion reconstruction and ligament balance. Identification of JL may be difficult, particularly in revision or primary cases of severe femoral condylar bone loss. We aimed to define the relationship between the epicondyles and the articular surface (AS) of the femur using computed tomography-based three-dimensional digital templating software. Methods The study included 127 knees with osteoarthritis of the knee below grade 2 on the Kellgren-Lawrence index. A perpendicular line was drawn from the medial and lateral femoral epicondylar processes to the most distal point of the AS, and the distance was measured in the axial and coronal planes. Femoral width was measured as the distance between the medial and lateral epicondyles. All distances described above were converted to a ratio by division with femoral width. Results On the axial plane, the distance from epicondyles to the posterior ASs was 29.4 ± 2.2 mm medially and 21.3 ± 2.1 mm laterally. The width of the distal femur was 75.2 ± 4.2 mm. On the coronal plane, the distances from epicondyles to the distal ASs were 25.2 ± 2.9 mm on the medial side and 21.3 ± 2.5 mm on the lateral side. The ratio of the distance from epicondyles to the distal and posterior ASs divided by the width of the femur was 0.39 ± 0.02, 0.28 ± 0.03, 0.34 ± 0.03, and 0.28 ± 0.03. Conclusions The distance from the epicondyles to the distal and posterior JLs correlates with the distal femur width. These findings may be useful in determining an appropriate JL.

Compressive failure analysis of composite honeycomb sandwich panels with impact damage and stepped-scarf repairs

Composite honeycomb sandwich panels (CHSPs) have been widely used in the aerospace industry owing to their lightweight and superior mechanical properties. However, these CHSPs are susceptible to impact damage, leading to a significant reduction in compressive strength and potentially jeopardize aircraft safety. It is crucial to investigate repair methods for CHSPs with impact damage. This paper aims to evaluate the repair performance of CHSPs with impact damage through an analysis of their compressive failure behaviors. To accomplish this, both experimental tests and advanced numerical models are employed. The numerical models for the intact, damaged and stepped-scarf repaired CHSPs are established using the progressive failure analysis model, cohesive zone model and sandwich plate theory. A good agreement is observed between the experimental results and numerical predictions of compressive failure behaviors. Moreover, the validated numerical models are successfully utilized for determining optimum repair parameters by parametric analysis of the repaired CHSPs. The establishment of these numerical models offers an accurate and cost-effective evaluation of repair performance for CHSPs with impact damage, highlighting the novelty and main contribution of this paper.