Performance Analysis on Retractable Landing Gear and Design of Ground Test System

Landing gears are one of the key components for large or middle unmanned aerial vehicles,and their working performances directly affect flying security and aircraft taking-off and landing performance.Thus,it is meaningful to study the retraction system.Based on CATIA and ADAMS software platforms,a virtual model of landing gear retraction system is built for performance test,and then dynamic simulation is carried out.Afterwards,a test system for landing gear retraction is established,and the test data are compared with the results acquired from dynamics simulation.The main factors which affect the dynamic performance of retractable landing gear are analyzed emphatically.The simulation results show that aerodynamic load has an impact on retraction time,the mass force affects extension process,and the oil hole size of hydraulic actuator has an effect on both retraction time and extension time.

GEOMETRIC DESIGN OF DEPLOYABLE/RETRACTABLE MAST

To simplify the complicated design process of deployable/retractable structures, a new design process is developed. The process is divided into three phases： the concept design phase, the model phase and the optimization phase. In each phase, different parameter targets have to be fulfilled. According to three phases, a deployable/retractable mast composed of four right triangle prism modules in the longitudinal direction is designed. It can be deployed and folded simultaneously by the linear movements of sleeve-joints. The deployable and retractable movement of the mast is analyzed and key joint forms are designed. Then bar diameters and joint forms are modified based on mast structural mechanics characteristics in the optimization phase. Finally a 1：1 scaled model mast is built to verify the design and the optimization. Analytical results show that the model mast has the advantages of simple locking mechanism, fewer types of joints and bars, so it can be easily manufactured.

Advancements in liver retraction techniques for laparoscopic gastrectomy

Traditionally,liver retraction for laparoscopic gastrectomy is done via manual methods,such as the placement of retractors through the accessory ports and using a Nathanson retractor.However,these techniques often posed issues including extra abdominal incisions,risk of liver injury or ischaemia,and the potential for compromised visualization.Over the years,the development of innovative liver retraction techniques has significantly improved the safety and efficacy of laparoscopic gastrectomy and similar other hiatal procedures.This editorial will comment on the article by Lin et al,and compare this to the other liver retractor techniques available for surgeons and highlight the pros and cons of each technique of liver retraction.

Retraction note to:Shugan Jieyu capsule effects on peripheral blood micro-124,micro-132,and brain-derived neurotrophic factor in patients with mild to moderate depression

In this retraction note,we have decided to retract an article published in World Journal of Psychiatry due to disagreement among the authors.

Retraction note:Predictive value of machine learning models for lymph node metastasis in gastric cancer:A two-center study

In this retraction note,we describe the World Journal of Gastrointestinal Surgery(WJGS)Editorial Office’s decision and reason for retracting an article published in WJGS,volume 16,issue 1.

Retraction control of motorized seat belt system with linear state observer

A design and verification of linear state observers which estimate state information such as angular velocity and load torque for retraction control of the motorized seat belt (MSB) system were described. The motorized seat belt system provides functions to protect passengers and improve passenger's convenience. Each MSB function has its own required belt tension which is determined by the function's purpose. To realize the MSB functions, state information, such as seat belt winding velocity and seat belt tension are required. Using a linear state observer, the state information for MSB operations can be estimated without sensors. To design the linear state observer, the motorized seat belt system is analyzed and represented as a state space model which contains load torque as an augmented state. Based on the state space model, a linear state observer was designed and verified by experiments. Also, the retraction control of the MSB algorithm using linear state observer was designed and verified on the test bench. With the designed retraction control algorithm using the linear state observer, it is possible to realize various types of MSB functions.

Dynamic analysis of a deployable/retractable damped cantilever beam

Deployable/retractable damped cantilever beams are a class of time-varying parametric structures which have attracted considerable research interest due to their many potential applications in the intelligent robot field and aerospace.In the present work,the dynamic characteristics of a deployable/retractable damped cantilever beam are investigated experimentally and theoretically.The time-varying damping,as a function of the beam length,is obtained by both the enveloped fitting method and the period decrement method.Furthermore,the governing equation of the deployable/retractable damped cantilever beam is derived by introducing the time-varying damping parameter,and the corresponding closed-form solution and vibration principles are investigated based on the averaged method.The theoretical predictions for transient dynamic responses are in good agreement with the experimental results.The dynamic mechanism analysis on time-varying damping offers flexible technology in mechanical and aerospace fields.

Mechanical performance study of the retractable pier column after stiffening

To solve the problem that the overlapping parts of a retractable pier column are prone to damage,this paper proposed the reinforcing measure of setting a stiffener ring at the bottom of the steel pipe.To study how the stiffener-ring parameters influence the mechanical properties of the pier column.12 scale model specimens(including nine specimens with stiffener-ring widths of 40,50,and 60 mm and three unstiffened comparison specimens)were tested under axial compression.Based on the test results,the specimen load-displacement,load-deflection,and load-strain curves were analyzed,and a finite-element model of a pier column under axial compression was established to determine the optimal stiffener size.The results show that setting a stiffener ring enhances the cooperative working ability between the steel pipe and the internal filling material and restrains the lateral deformation of the pier column,thereby improving the ultimate bearing capacity and overall stability of the pier column.The ultimate bearing capacity of the pier column is related to the width and thickness of the stiffener ring.The optimal size of the stiffener ring of the model pier column is 70 mm in width and 4 mm in thickness.The present research results provide a reference for designing compressible pier columns and column stiffening in mines and have important practical significance.

Asymptotic solutions for the asymmetric flow in a channel with porous retractable walls under a transverse magnetic field

The self-similarity solutions of the Navier-Stokes equations are constructed for an incompressible laminar flow through a uniformly porous channel with retractable walls under a transverse magnetic field. The flow is driven by the expanding or contracting walls with different permeability. The velocities of the asymmetric flow at the upper and lower walls are different in not only the magnitude but also the direction. The asymptotic solutions are well constructed with the method of boundary layer correction in two cases with large Reynolds numbers, i.e., both walls of the channel are with suction, and one of the walls is with injection while the other one is with suction. For small Reynolds number cases, the double perturbation method is used to construct the asymptotic solution. All the asymptotic results are finally verified by numerical results.

Peripheral Neuropathy after Open Abdominal Surgery with Self-Retaining Retractors. A Systematic Review of Randomised and Non-Randomised Clinical Trials

Objectives : A systematic review was undertaken to evaluate the effectiveness of incision retention available to surgeons conducting open abdominal or pelvic surgeries. Both the ability of the retractor to retain the wound and harm to the patient due to the retractor were reviewed. Methods : A search was conducted using the following databases: EMBASE, PubMed, BIOSIS, Engineering Village, Web of Science, Best practice, Science Direct, CRCnet BASE, Proquest, Wiley Online Library, and Comprehensive Biomaterial. Results : What the articles found were then narrowed down to those which matched the objective of the review. This resulted in ten articles to review. Two reviewers reviewed and summarized the articles. Femoral neuropathy was found to be a common complication due to Retractors. Other outcomes analysed or studied were found to be infected, postoperative pain and exposure provided. Femoral neuropathy can be estimated to occur at a rate between 2.6% and 7.5% in open pelvic and abdominal surgeries. The Alexis O-ring retractor was found to lower the required morphine intake following surgery when compared to the Belfour retractor. Conclusions : There is a lack of high quality/high levels of evidence studies that have been conducted on Retractors. Femoral neuropathy is the outcome most commonly documented in relation to Retractors. Surgeons need to be aware about the use and implementations of the retractors. Care should be taken in protecting the blades and during long surgery relocating retractors should be considered.

Reliability analysis of retractable drill bit with air reverse circulation used for drilling while casing

Casing-while-drilling(CWD)with down the hole(DTH)hammer drilling technology has been widely used in unconsolidated formations,due to its advantages in protecting the borehole wall,excellent rock cuttings capacity,and fast penetration rate in hard rock.As an important component of the CWD system,the structure of the retractable drill bit needs not only to ensure to form stronger reverse circulation,but also to be expandable or retractable as needed,otherwise the drill bit cannot be lift and put down smoothly in the casing,and may lead to drilling accidents.This paper developed a new type of reverse circulation DTH hammer drill bit used for CWD drilling technology.The retractable performance of this type of drill bit is studied using ADAMS software.The results show that it is smoothly expandable and retractable as designed under the conditions of the weight of the bit(WOB)of 0.5–2.0 t and the rotation speed of 30–60 r/min.To investigate the reverse circulation effect of the drill bit,Fluent software was used to simulate the flow characteristic inside it.The simulation results indicated that it can form strong reverse circulation,and the entrainment ratio h can reach 9.5%.

A systematic review of the treatment of lower eyelid retraction and our attempt of a dermal-orbicularis oculi suspension flap

Lower eyelid retraction describes the inferior displacement of the lower eyelid with or without inversion or ectropion.Based on the causes of lower eyelid retraction,we divided the forming factors of lower eyelid retraction into three categories:(1)change in the balance of forces associated with the lower eyelid margin;(2)excessive loss of lower eyelid volume;(3)changes in the relative position of the eyeball and lower lid margin.In this review,the corresponding treatment methods are elaborated on individually for the above three forming factors.We also reported,for the first time,a new treatment for lower eyelid retraction.We created a dermal-orbicularis oculi suspension flap on the lateral side of the canthus and suspended it upward and inward on the dense connective tissue over the lateral bony surface of the orbital rim.The longest follow-up time was one year,and the results were satisfactory.

Dynamical Analysis of a Novel Spherical Robot with Retractable Arms

A novel structure of a spherical robot with retractable arms was presented in order to fulfill the requirements of omni-direction movement and operation mission. Under the assumption of rolling without slipping, nonholonomic constraints were revealed and a dynamics model of the proposed robot was constructed by use of Kane＇s method. Numerical simulations about rectilinear motion and sigmoid curve motion of the system were carried out in Matlab, and as a comparison, the same trajectories were also implemented by a virtual prototype in ADAMS, which validate the derived dynamical model accordingly. With the derived dynamical model, torques/forces of joints were analyzed. The results indicate the disturbance forces or torques on each joint are not zero under the state of sphere moving, and with rational planning for the trajectory of the robot, there will be a great decrease of the disturbance forces or torques acting on the spherical caps and arms.

A comparative study on characteristics of retracted publications across different open access levels

Purpose:Recently,global science has shown an increasing open trend,however,the characteristics of research integrity of open access(OA)publications have rarely been studied.The aim of this study is to compare the characteristics of retracted articles across different OA levels and discover whether OA level influences the characteristics of retracted articles.Design/methodology/approach:The research conducted an analysis of 6,005 retracted publications between 2001 and 2020 from the Web of Science and Retraction Watch databases.These publications were categorized based on their OA levels,including Gold OA,Green OA,and non-OA.The study explored retraction rates,time lags and reasons within these categories.Findings:The findings of this research revealed distinct patterns in retraction rates among different OA levels.Publications with Gold OA demonstrated the highest retraction rate,followed by Green OA and non-OA.A comparison of retraction reasons between Gold OA and non-OA categories indicated similar proportions,while Green OA exhibited a higher proportion due to falsification and manipulation issues,along with a lower occurrence of plagiarism and authorship issues.The retraction time lag was shortest for Gold OA,followed by non-OA,and longest for Green OA.The prolonged retraction time for Green OA could be attributed to an atypical distribution of retraction reasons.A comparative study on characteristics of retracted publications across different open access levels Research limitations:There is no exploration of a wider range of OA levels,such as Hybrid OA and Bronze OA.Practical implications:The outcomes of this study suggest the need for increased attention to research integrity within the OA publications.The occurrences offalsification,manipulation,and ethical concerns within Green OA publications warrant attention from the scientific community.Originality/value:This study contributes to the understanding of research integrity in the realm of OA publications,shedding light on retraction patterns and reasons across different OA levels.

Amend:An integrated platform of retracted papers and concerned papers

Purpose:The notable increase in retraction papers has attracted considerable attention from diverse stakeholders.Various sources are now offering information related to research integrity,including concerns voiced on social media,disclosed lists of paper mills,and retraction notices accessible through journal websites.However,despite the availability of such resources,there remains a lack of a unified platform to consolidate this information,thereby hindering efficient searching and cross-referencing.Thus,it is imperative to develop a comprehensive platform for retracted papers and related concerns.This article aims to introduce“Amend,”a platform designed to integrate information on research integrity from diverse sources.Design/methodology/approach:The Amend platform consolidates concerns and lists of problematic articles sourced from social media platforms(e.g.,PubPeer,For Better Science),retraction notices from journal websites,and citation databases(e.g.,Web of Science,CrossRef).Moreover,Amend includes investigation and punishment announcements released by administrative agencies(e.g.,NSFC,MOE,MOST,CAS).Each related paper is marked and can be traced back to its information source via a provided link.Furthermore,the Amend database incorporates various attributes of retracted articles,including citation topics,funding details,open access status,and more.The reasons for retraction are identified and classified as either academic misconduct or honest errors,with detailed subcategories provided for further clarity.Findings:Within the Amend platform,a total of 32,515 retracted papers indexed in SCI,SSCI,and ESCI between 1980 and 2023 were identified.Of these,26,620(81.87%)were associated with academic misconduct.The retraction rate stands at 6.64 per 10,000 articles.Notably,the retraction rate for non-gold open access articles significantly differs from that for gold open access articles,with this disparity progressively widening over the years.Furthermore,the reasons for retractions have shifted from traditional individual behaviors like falsification,fabrication,plagiarism,and duplication to more organized large-scale fraudulent practices,including Paper Mills,Fake Peer-review,and Artificial Intelligence Generated Content(AIGC).Research limitations:The Amend platform may not fully capture all retracted and concerning papers,thereby impacting its comprehensiveness.Additionally,inaccuracies in retraction notices may lead to errors in tagged reasons.Practical implications:Amend provides an integrated platform for stakeholders to enhance monitoring,analysis,and research on academic misconduct issues.Ultimately,the Amend database can contribute to upholding scientific integrity.Originality/value:This study introduces a globally integrated platform for retracted and concerning papers,along with a preliminary analysis of the evolutionary trends in retracted papers.

Rotational Intravascular Multidirectional Ultrasound Catheter for Sonothrombolysis of Retracted Clots:An in Vitro and in Vivo Study

Thromboembolism in blood vessels poses a serious risk of stroke,heart attack,and even sudden death if not properly managed.Sonothrombolysis combined with ultrasound contrast agents has emerged as a promising approach for the effective treatment of thromboembolism.Recent reports have highlighted the potential of intravascular sonothrombolysis as a safe and effective treatment modality for deep vein thrombosis(DVT).However,its efficiency has not been validated through in vivo testing of retracted clots.This study aimed to develop a miniaturized multidirectional transducer featuring two 4-layer lead zir-conate titanate(PZT-5A)stacks with an aperture size of 1.4 mm1.4 mm,enabling both forward-and side-looking treatment.Integrated into a custom two-lumen 10-French(Fr)catheter,the capability of this device for intravascular sonothrombolysis was validated both in vitro and in vivo.With low-dose tissue plasminogen activators and nanodroplets,the rotational multidirectional transducer reduced the retracted clot mass(800 mg)by an average of 52%within 30 min during in vitro testing.The lysis rate was significantly higher by 37%than that in a forward-viewing transducer without rotation.This improvement was particularly noteworthy in the treatment of retracted clots.Notably,a long-retracted clot(>10 cm)was successfully treated within 40 min in vivo by creating a flow channel with a diameter>4 mm in a porcine DVT model.In conclusion,these findings strongly suggest the potential of this technique for clinical applications in sonothrombolysis,offering a feasible solution for effectively treating thromboembolism,particularly in challenging cases involving retracted clots.

A new technique for correction of iatrogenic upper eyelid retraction by using a composite flap of the orbicularis muscle and fascia on the anterior surface of the tarsal plate

Background:Upper eyelid retraction is a challenging complication of cosmetic upper eyelid blepharoplasty.To avoid extra trauma,we developed a new technique for correcting iatrogenic upper eyelid retraction by postmigrating a compound flap of the orbicularis muscle and fascia(OFC)on the anterior surface of the tarsal plate.This method extends the aponeurosis of the levator palpebrae superioris muscle(LPS),which can achieve a good correction for post-blepharoplasty retraction.Methods:We collected data from 15 patients with mild to moderate iatrogenic upper eyelid retraction who were treated at our hospital between February 2017 and December 2019.The OFC was used to replace the missing part of the LPS,and post-migration of the LPS and fixation of the OFC to the tarsal margin were conducted.Postoperative outcome measurements included postoperative binocular symmetry,double eyelid smoothness,eyelid fullness,margin reflex distance(MRD1),degree of eyelid closure,and exposure keratitis.The patients were followed-up at seven days,one month,and six months postoperatively.Results:One patient with moderate eyelid retraction showed undercorrection 6 months postoperatively,with the upper eyelid margin located at the upper edge of the pupil.The remaining patients had the upper eyelid margin stabilized at 1.0–2.0 mm below the upper corneal margin.Other observational indicators were satisfactory,including binocular symmetry,double eyelid fluency,and eyelid fullness.During the follow-up,no exposure keratitis was identified.The MRD1 indexes after the operation were significantly different(P<0.001)from those before the procedure.Conclusions:Extension and post-migration of the LPS using the orbicularis muscle and OFC structure can effectively correct mild iatrogenic eyelid retraction after ptosis with less damage and good postoperative eyelid morphology and closure function.

Retraction note:Clinical analysis of colistin sulfate in the treatment of pneumonia caused by carbapenem-resistant Gram-negative bacteria

In this retraction note,we describe the World Journal of Clinical Cases(WJCC)Editorial Office’s decision and reason for retracting an article published in WJCC,volume 12,issue 13.

Retraction note to:RNA-binding protein CPSF6 regulates IBSP to affect pyroptosis in gastric cancer

The authors have decided to retract the article published on World J Gastrointest Oncol(2023)for further consideration due to data errors and some misunderstandings in communication.

Retraction note to:Association between triglyceride-glucose index and colorectal polyps:A retrospective cross-sectional study

We have decided to retract the above article because we have concluded that the limitations in our data sample may potentially lead to misinterpretation of the findings.