Tightening Procedure Research Articles

Patient satisfaction following treatment with micro-focused ultrasound with visualization: A retrospective cross-sectional study.

There has been increased public interest in noninvasive skin tightening procedures that produce the best possible cosmetic outcomes. Micro-focused ultrasound with visualization (MFU-V) is a secure, efficient method of treating skin laxity approved by the FDA. Few studies have assessed patient satisfaction following MFU-V. A retrospective cross-sectional study was conducted between January 2022 and 2023. After obtaining the author's permission, a previously examined and published questionnaire was used to contact all participants (n=98) who had received MFU-V therapy in a private clinic in Riyadh, Saudi Arabia, between 2016 and 2020 via phone interview. All 98 patients undergoing MFU-V were female. About two-thirds indicated they were satisfied or very satisfied with the results. Those receiving treatment around the eye and submentum reported lower satisfaction levels than those receiving therapy in other regions. The number of treatment locations and satisfaction were positively correlated. Patients treated by consultants rather than laser experts reported much higher satisfaction levels. Satisfaction and the amount of time for improvement to occur following treatment were correlated statistically. Pain and tingling were the most frequent adverse effects the respondents reported, followed by skin redness and swelling; however, adverse effects were not connected with satisfaction. Cost (78.6%) was cited as the main deterrent to seeking treatment again. MFU-V, an FDA-approved procedure, has proven effective and safe for treating facial and neck skin laxity. When patients are carefully selected and physicians properly trained, higher satisfaction is achieved.

An optimal expansion planning of power systems considering cycle-based AC optimal power flow

This paper presents a novel mixed-integer linear optimization formulation of the AC network-constrained, cost-based, integrated expansion planning problem. The formulation is used to determine the investment needs per technology including the location and sizing of new generation, energy storage, and transmission network assets in a future low-carbon power system. To reduce the size of the resulting problem, the AC optimal power flow (AC-OPF) model is represented in a compact way using cycle constraints. A bound tightening procedure is also considered to reduce the search space and improve the solver performance by adjusting the voltage bounds within the AC-OPF. Contrary to typically used formulations of the integrated expansion planning problem, the constraints considered here include all main aspects of system operation, namely unit commitment, energy storage system management, AC-OPF, and reactive power compensation. Thus, in this paper, we examine how both the proposed transmission expansion modeling developments and the interrelation of the integrated planning constraints affect the computation of the solution to the expansion planning problem. The performance of this formulation is assessed on the RTS-GMLC test system by computing the expansion plan and comparing it with the results of three other expansion planning formulations most frequently employed in the recent literature to address the integrated expansion planning problem for medium to large-scale systems. Expansion plans are computed and compared for different case studies and multiple scenarios. According to the comparative analysis, neglecting the AC-OPF or the unit commitment constraints can increase the total system costs by 7.10%–9.57% or 6.29%–8.39%, respectively. Unlike other modeling approaches, the proposed approach does not rely on simplifications that impact the quality of the solution. Thanks to the incorporated cycle-based AC-OPF constraints and the consideration of a bound tightening procedure, the computation time is reduced by 17.67%–27.21%.

Experimental investigation on stress state and deformation in bolts through tightening of perfect flange connections

AbstractThe fatigue loads of bolts in ring flange connections are significantly influenced by the pressure body between the compressed flanges, which in turn depends on two main scattering parameters ‐ geometric flange imperfections and the preload level. Depending on the tightening method and geometric boundary conditions, shear and bending stresses occur in addition to the axial stress in the bolt during prestressing of the connection. This multiaxial stress condition leads to different plastic deformations in the threads and thereby influence the performance respective the maximum achievable preload of tightening methods. In accordance with the objective, the authors identify the stress state in HV‐bolts during installation for different tightening procedures through experimental testing. Based on a comparison of the strain measurements with the 3D scan of the bolt geometry, this study evaluate to what extent the initial imperfections corresponds to bolt bending. Derived from the scope of a joint national research project, this contribution point out that the yield controlled tightening ensure prestresses close to the individual yield strength of the bolt within a narrow scatter.

Sequential Load Restoration With Soft Open Points and Time-Dependent Cold Load Pickup for Resilient Distribution Systems

Global changes in climate conditions and increasing number of weather-related disasters in the world have elevated the quest for better load restorations in power distribution systems. This paper proposes a distribution system restoration (DSR) model where non-exponential time-dependent cold load pickup (CLPU) characteristics and soft open point operations are simultaneously addressed. We develop a time-dependent CLPU model for attaining a more realistic and secure DSR in which we demonstrate that the traditional delayed exponential model (DEM) for a long outage duration is a special case of the adopted CLPU model. The current soft open point (SOP) models would typically relax the operation constraints without devising any tightening procedures, which might lead to inaccurate or even infeasible SOP states. In this paper, we analyze the reasons traditional SOP constraints would lead to unsecure operations and present a set of novel SOP operation constraints for recovering bindings. Also, we adopt the sequential second order cone programming (SSOCP) algorithm to establish the sequential framework of DSR and solve the proposed model effectively. Our presented case studies discuss the rationality of the proposed DSR model and algorithm.

Background Information on the Bolt Tightening Qualification Procedure (BTQP)

The execution of preloaded stainless steel bolting assemblies is currently only permitted according to EN 1090-2 if procedure tests are carried out. Nevertheless, it has be shown in various previously and recently conducted studies that preloading of bolting assemblies and threaded rods made of stainless steel is in principle feasible and that reliable tightening procedures can be developed. Thus, there is an urgent need for clear guidance and normative implementation as EN 1090-2 does not give any procedure to qualify these bolting assemblies for preloading. This paper aims to present background information on the Bolt Tightening Qualification Procedure (BTQP) for stainless steel bolting assemblies, which was already implemented in the recently drafted ISO 17607-6.

Experimental study on mechanical properties and tightening method of stainless steel high-strength bolts

The lack of product specification of stainless steel high-strength bolts has restricted the application of high-strength bolts in stainless steel structures. Existing studies have found that stainless steel bolts experience thread galling during the tightening procedure, making it impossible to apply preload. Different studies have obtained different torque coefficient values. In this paper, a series of tests were carried out on two types of grade 10.9 stainless steel high-strength bolts and two types of ordinary stainless steel bolts, and the tensile strength, shear strength, hardness and preload level were obtained. The results show that the yield strength, tensile strength and elongation after break of the new stainless steel high-strength bolts can reach 1122 MPa, 1147 MPa and 16.3% respectively, proving that the grade 10.9 stainless steel high-strength bolts meet the requirements of the conventional grade 10.9 high-strength bolts. Tightening tests on stainless steel bolts with lubricant were carried out and it was found that the friction-reducing lubrication effect was related to the curing time of the lubricant. The lubricant Molykote D-321R Spray was found to be more effective in reducing friction and preventing thread galling in stainless steel bolts. With the optimum curing time at room temperature of 12 h, the lubricant can reduce the torque coefficient to about 0.080, meeting the torque coefficient limit for high-strength bolts. In the end, the preload level, torque coefficient and torque level for construction for stainless steel high-strength bolts are recommended for engineering applications.

Preload and friction in an implant–abutment–screw complex including a carbon-coated titanium alloy abutment screw: an in vitro study

PurposeAn experimental approach was designed to measure the preload force, the coefficient of friction and the component of the tightening torque that is needed to surmount the thread-friction in an implant–abutment–screw complex that includes a carbon-coated screw. With the determined preload values the coefficient of friction was calculated.Methods25 unused complexes, containing an implant, an abutment and a carbon-coated titanium alloy abutment screw, were tested. A custom load frame with two load cells and associated electronics was used. The threads were not lubricated. All abutment screws were torqued ten times to 25 Ncm. The produced preload values and a force that was proportional to the thread-friction component of the tightening torque were recorded.ResultsMean preload values decreased significantly with the number of repetitions (p < 0.0001) from initially 329.9 N ± 33.3 (range 255.7 to 383.9) to 253.7 N ± 36.8 (range 200.1 to 332.5) for the last tightening procedure. The corresponding change in the calculated coefficient of friction was 0.33 ± 0.04 (range 0.28 to 0.43) to 0.44 ± 0.07 (range 0.32 to 0.56). For the thread-friction no corresponding trend for consecutive tightening repetitions could be noticed.ConclusionsIn the investigated implant–abutment units, repeated use of a coated abutment screw appears to increase the friction of the screw head and thereby decrease the preload. These results indicate that a pre-used coated implant–abutment–screw will fail reaching optimal screw preload.Graphical abstract

Development of the Guidance on the Tightening of Large Anchor Rods of Support Structures for Sign and Luminaires

Across the United States, various state Departments of Transportation (DOTs) are finding that the base anchor-rod nuts on critical support structures for overhead signs are coming loose. Retightening loose nuts imposes a significant drain on state DOT resources. In addition, the loosening of these nuts increases the failure risk of tall and overhanging structures. In many of the inspection engineer’s observed cases, anchor-rod nuts were loose immediately after installation. Even after tightening, it was found that anchor-rod nuts had consistently come loose just 2 years after retightening. The objective of this study was to evaluate the resistance to the loosening of anchor-rod tightening procedures proposed by Chen et al. and to develop improvements to the procedures based on stakeholder feedback. To achieve this objective, field deployment of the previously developed procedures was conducted on multiple sites. After field deployment, improvements to the Chen et al. procedure were investigated on a full-size laboratory specimen to ensure revisions did not affect connection performance. Overall, it was found that the pretension levels proposed by Chen et al. were effective, and the revised procedures only use torque, or force-controlled tightening, as opposed to displacement-controlled turn-of-nut.

The 50 most cited articles and science mapping analysis of vaginal tightening.

The study was aimed at exploring the 50 most cited articles related to vaginal tightening. The papers were searched through the Thomson Reuters Web of Science on 30 July 2022, and were ranked by the total number of citations. The included articles were analyzed for author, journal, country, number of citations, keywords, subject matter, and level of evidence. The search output was also imported into VOSviewer. The 50 most cited articles were cited a combined total of 2,558 times. The papers were published between 1990 and 2020, of which 86% were published between 2010 and 2020. They included 38 original articles, 8 reviews, 3 editorial articles, and 1 letter. Most articles were published in gynecology-related journals (n=30, 60%). The articles covered a wide range of topics, the most common being laser/radiofrequency treatment, vaginal tightening procedures, and urinary incontinence. The majority presented findings supported by level IV or V evidence. Through co-occurrence analysis, high-frequency words and countries were displayed well. The study shed light on frequently read articles and influential topics about vaginal tightening. The highly cited literature mainly focused on laser or radiofrequency treatments and gynecologists currently dominate the highly cited literature on vaginal tightening. The articles related to surgical treatments are low in number and evidence level so far. The co-occurrence analysis reveals the hot research content and active countries in the field. In general, the study provides useful evidence for future research and educational materials.

Computation of invariant sets via immersion for discrete-time nonlinear systems

In this paper, we propose an approach for computing invariant sets of discrete-time nonlinear systems by lifting the nonlinear dynamics into a higher dimensional linear model. In particular, we focus on the maximal admissible invariant set contained in some given constraint set. For special types of nonlinear systems, which can be exactly immersed into higher dimensional linear systems with state transformations, invariant sets of the original nonlinear system can be characterized using the higher dimensional linear representation. For general nonlinear systems without the immersibility property, approximate immersions are defined in a local region within some tolerance and linear approximations are computed by leveraging the fixed-point iteration technique for invariant sets. Given the bound on the mismatch between the linear approximation and the original system, we provide an invariant inner approximation of the maximal admissible invariant set by a tightening procedure.

The Role of Subcutaneous Radiofrequency-Assisted Liposculpture in the Facial Plastic Surgeon's Practice.

Importance: Percutaneous radiofrequency-based skin tightening procedures can offer patients an option to undergo a potential treatment for skin laxity and excess adipose of the face and neck with less downtime, lower cost, and decreased risk of complications compared with more aggressive open procedures such as neck lift, face and neck lift, and platysmaplasty. Observations: FaceTite and AccuTite can safely yet effectively deliver energy into the subdermal space, targeting the dermal collagen network and deeper fascial layer. Ideal candidates have early jowl formation, mild to moderate skin laxity, and submental adiposity. Relevance & Conclusions: From the perspective of facial plastic surgeons, these procedures can enhance the volume of an aesthetic practice by welcoming patients who may not otherwise present for face and neck rejuvenation out of fear from surgery. Furthermore, many of these minimally invasive patients will ultimately return for surgical rejuvenation later in life.

The Importance of Identifying Meibomian Gland Inversion in Patients With Floppy Eyelid Syndrome.

Floppy eyelid syndrome (FES) is a common and underdiagnosed condition characterized by eyelid hyperlaxity with reactive palpebral conjunctivitis that can cause ocular irritation. It may be associated with meibomian gland dysfunction (MGD) and secondary tarsal curling, resulting in upper eyelid meibomian gland inversion (MGI) in the absence of obvious marginal entropion. To highlight the possible significance of MGI in patients with FES and report findings and outcomes in patients with concomitant MGI and FES undergoing correction of MGI with or without upper eyelid horizontal tightening. Retrospective, 5-year, noncomparative, single-center study of patients with FES and MGI, treated with MGI correction, with or without upper eyelid horizontal tightening, under the supervision of a single surgeon. Preoperative symptoms, surgical outcomes, complication rates, and postoperative symptoms were recorded. A total of 13 eyes of 9 patients were treated with MGI surgery over the study period. Seven were male. Mean age at the surgery was 63 (range 42-81) years. Two OSs, 3 ODs, and 4 OUs were treated. All patients were "cotton-tip test" positive, and 77% (10/13) had MGI-related superior corneal fluorescein staining. Three patients (33%) had previous standard tightening procedures with recurrence of symptoms within 5 to 24 (mean 16) months. Repeat horizontal tightening had been considered in all these cases before referral to our unit. Mean follow-up was 20 months. Eight patients (88.9%) had improvement of symptoms (n = 3, full resolution; n = 5, partial resolution). All patients demonstrated restoration of the normal anatomical position of the meibomian glands. Superior punctate staining resolved in all eyes. This study provides a proof of concept that upper eyelid MGI can be present and symptomatic in patients with FES. It may help explain cases where symptoms persist or recur early following standard upper eyelid horizontal tightening. Where superior corneal punctate staining and a positive cotton-tip test exist, surgical correction of MGI, alongside horizontal tightening, may provide better, and longer-lasting symptomatic relief. This study provides evidence for the need for a prospective study to evaluate the contribution of MGI in patients with FES.

Acute cataract by a high-intensity focused ultrasound procedure: a case report

BackgroundWe report a case of acute onset of cataract after eyelid rejuvenation tightening with intense focused ultrasound (IFUS) treatment without using a protection device.Case presentationA 47-year-old female patient presented at the outpatient clinic with blurred vision in her left eye immediately after undergoing an eyelid tightening procedure, using IFUS, seven days prior. The patient had decreased vision in her left eye, caused by an acute cataract with several drop-like opacities and a rosette-like posterior subcapsular cataract. One month after her first visit, the patient’s visual acuity in her left eye decreased to 20/630. A Swept-Source Anterior Segment optical coherence tomography confirmed that the posterior capsule was not ruptured. The patient underwent uneventful phacoemulsification cataract surgery with intraocular lens implantation, which resulted in full visual recovery.ConclusionsThis case emphasized the need to evaluate possible ocular side effects, resulting from periocular IFUS without a protection device, including severe cataract requiring surgery.

A Novel Technique Combining Human Acellular Dermal Matrix (HADM) and Enriched Platelet Therapy (EPT) for the Treatment of Vaginal Laxity: A Single-Arm, Observational Study.

BackgroundThere is a paucity of knowledge about cosmetic vaginal tightening procedures; therefore, the present study aimed to describe the clinical effects of a novel combination technique of human acellular dermal matrix (HADM) and enriched platelet therapy (EPT) for the treatment of vaginal laxity.MethodsThis single-arm, observational study was conducted on 52 patients with grade II to III vaginal relaxation. HADM biological band (U-shaped) was implanted in these patients by submucosal puncture in vagina under anesthesia. This was followed by thrice administration of EPT injection, once at the time surgery followed by each dose at a time interval of one month. Patients were followed up for a period of 6 months based on Female Sexual Function Index (FSFI) and Vaginal Health Index (VHI) scores. Patient satisfaction was measured using Visual Analogue Score (VAS).ResultsAbout 52 women with median age of 39 years were included in the study. The average time reported to complete HADM surgery was reported as 27 minutes. Following implantation, it was found that labia minora was significantly closed and perineal length was increased from 1.5 to 2.2 cm. Moreover, there was improvement in elasticity, contractility and lubricity of vaginal mucosa. The sexual function scores from pre- to post-surgery were significantly increased (7.95 vs. 30.09; p value: <0.001). The mean VHI score also increased significantly after 6 months of treatment (mean ± S.D. before vs after treatment: 11.2 ± 3.3 vs. 19.6 ± 4.1, P < 0.0001). The mean VAS after surgery was 1.61 ± 0.31. About 96% of the patients did not feel any pain after treatment at 6-month follow-up. No adverse effects were reported in this study.ConclusionsThese findings supported that combination treatment with HADM and EPT was safe and associated with both improved vaginal laxity and sexual function. These results may provide a novel surgical technique for this prevalent and undertreated condition.Level of Evidence IV: Therapeutic Study This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

A modified Altis® mid-urethral sling that allows immediate post-operative adjustment: experience in 197 patients.

The transobturator mid-urethral Altis® "mini-sling" uses a static and a dynamic anchor on either end of a pulley suture for intraoperative tension adjustment. Given the potential for incorrect tensioning with sling placement, we adopted a modification for post-operative adjustment should stress urinary incontinence (SUI) persist. The objective is to describe technique, rate of postoperative adjustment driven by patient symptoms, and impact of preoperative/intraoperative variables. In this single-surgeon experience, retrospective chart review, demographic and clinical data were collected on patients who received the Altis® sling for SUI between 2014 and 2019. We used descriptive statistics and three-group comparison tests to assess difference in variables among tightening, loosening, or no adjustment. Altis® sling placement was performed on 197 female patients with an average age of 58.7years. Eighty-four percent (165/197) did not receive post-operative adjustment. Of the 32 patients with post-operative adjustment, 8 (4.1%) had loosening and 24 (12.2%) had tightening at an average of 10.5days post-operatively. All tightening procedures were done in the clinic. Of the 8 patients with post-operative loosening, 6 were performed in clinic and 2 in the operating room. Preoperative and intraoperative variables were not significantly different among tightening, loosening, and no adjustment cohorts. This modification of the Altis® sling provides surgeons with the ability to tighten and loosen the sling for persistent SUI. All tightening and most loosening procedures were able to be performed in the clinic. The ability to easily tighten a sling in the early post-operative period may be a critical advantage.

Experimental Investigation of the Fatigue Lifespan of Anchor Bolts with Consideration of Loading History

Preloaded bolted connections are one of the most used approaches for anchoring steel structures and equipment. Preload is induced by a mechanical tightening of the nut with the required torque. In the case of anchor bolts embedded in a concrete base, the prescribed tightening procedure has to be followed for safe and reliable operation. The present paper addresses the problem of anchoring a new casting pedestal using the original anchor bolts. The aim was to verify the original anchoring system’s reliable and safe operation, taking into account the current condition of the bolts. The analysed anchoring bolts are subjected to cyclic (disappearing) stress during the rotation of the casting pedestal. If the interplays between the anchor bolt and the concrete foundation were damaged, production would shut down, resulting in high economic losses. For this reason, the authors used a modified nut with a lightened first thread when investigating the actual state of the anchoring and setting the required preload. The shape and dimensions of the nut were determined based on the results of numerical modelling. The experimental measurements consisted of two phases. In the first phase, the values of axial forces in the anchor bolts at the required preload were set using the designed dynamometers. The second phase was focused on the operational measurements. The methodology of measuring the axial forces and the interpretation of the results obtained, including a comprehensive view of the anchoring safety, provides relevant evidence of the functionality and effectiveness of the proposed solution. Based on the results of the operational measurement and the prescribed handling of the casting pedestal, the lifespan of the anchoring was determined to be 3650 days under the loading cycles to date.

Tightening Procedures for Proper Installation of Anchor Rods in Ancillary Structures

In the last 2 decades, many ancillary structures have collapsed, with several instances traceable to loose anchor nuts. According to a quality assurance inspection conducted by the Virginia Department of Transportation (VDOT) in 2012, approximately 30% of the anchor nuts on the inspected ancillary structures across the state of Virginia were found to be loose. The exact cause of the loose anchor nuts is not known; however, one theory is that specified tightening procedures were not properly followed or were not adequate. Currently, a turn-of-the-nut method is used for the tightening of anchor nuts on double-nut moment connections at the base of ancillary structures. This research reviewed current tightening procedures for anchor nuts on ancillary structures. The relationship between three critical tightening parameters—applied torque, nut rotation, and pretension in the rod—was examined. One hundred galvanized steel anchor rods of five different diameters and three different grades were tested. The experimental tests serve as a benchmark to validate the current tightening procedures, as well as to recommend changes.

Nonlinear interaction effect on main cable clamp bolts tightening in suspension bridge

Elastic interaction effect commonly exists in the assembly of multi-bolted joint. It is defined as the loss of tension forces in some bolts due to progressively tightening of neighboring bolts. Main cable clamp is a large size bolted joint used in suspension bridge. Investigation on the interaction effect of the clamp bolt tightening has seldom been reported. This article presents a field experiment to study the interaction effect on the clamp bolt tightening. In the experiment, three types of clamp and three tightening sequences were included. Then, finite element models considering the actual nonlinear transverse compressed behaviour of main cables were devised to simulate the bolt tightening procedures, thus providing an effective numerical tool to understand the nonlinear interaction effect on clamp bolts tightening. The experimental results provide validations for subsequent numerical studies, showing that the devised finite element modeling method can effectively predict nonlinear deformation of the main cable and the residual tension force of the clamp bolts. Moreover, the tightening efficiency of different tightening sequeces are discussed based on the experimental and the numerical results. Conclusions can be drawn that for the clamps with much longer length and much more rows of bolts, the degree of the nonlinear interaction effect tends to be higher. The side-to-centre bolt tightening sequence is more effective than the centre-to-side sequence.

Reconstruction of lower lip defects with free super-thin anterolateral thigh flap.

Lower lip is a vital organ with important functions as well as aesthetic importance. It is critical to provide an aesthetically appealing lower facial subunit with maintenance of understandable speech and oral competence. Achieving these targets is very difficult especially in total lower lip defects. This report presents a technique using super-thin anterolateral thigh (ALT) flaps with fascia graft for reconstruction of large, complex oral sphincter defects. Six patients with squamous cell carcinoma (SCC) and one patient with a gunshot injury were presented in this report. All of them had full-thickness defects including skin, orbicularis muscle and oral mucosa. The mean age was 58 (range, 32-85) years. Defects of the lower lip were reconstructed with a super-thin ALT flap. Super-thin flaps were obtained by planning as close to the knee as possible and elevating at the level of superficial fascia. The fascia graft was used for achieving lip suspension. Overall flap survival was 100%. The flap size ranged from 8 × 6 cm to 14 × 10 cm. The follow-up periods ranged from 6 to 14 months. All the patients achieved acceptable oral competence, both in the resting condition and during speaking and eating, except for one patient who had a drooping lower lip developed in the post-operative 3rd month and underwent a secondary tightening procedure. Another patient needed liposuction due to bulky appearance. Super-thin ALT flaps seem to be a useful option for functional and aesthetic reconstruction of extensive lip defects.

A convex optimization and iterative solution based method for optimal power-gas flow considering power and gas losses

Optimal power-gas flow (OPGF) is an important problem for the coordinated operation of an integrated electricity and natural gas system (IEGS). However, it is a challenge to solve the OPGF problem due to its non-convexity. This paper proposes a new OPGF method considering both power losses and gas losses based on convex optimization to balance modeling accuracy and tractability. As for power system modeling, a DC power flow model with power losses embedded as equivalent loads is used to approximate the nonlinear AC power flow model. As for gas system modeling, (1) a second-order cone (SOC) relaxation method is proposed to address the non-convex Weymouth equations, and the tightness of the SOC relaxation is guaranteed by introducing a penalty term and an iterative tightening procedure based on the convex envelope. (2) Gas losses of compressors are also modeled as equivalent loads and two more penalty terms on compressors are introduced to improve the accuracy of gas loss modeling. The OPGF problem is finally formulated as a mixed-integer convex programming model with unknown equivalent loads, and an iterative solution approach is then developed to solve the problem. Numerical results validate the effectiveness of the proposed OPGF method.