Optimization of Fixture Number in Large Thin-Walled Parts Assembly Based on IPSO

There are lots of researches on fixture layout optimization for large thin-walled parts.Current researches focus on the positioning problem,i.e.,optimizing the positions of a constant number of fixtures.However,how to determine the number of fixtures is ignored.In most cases,the number of fixtures located on large thin-walled parts is determined based on engineering experience,which leads to huge fixture number and extra waste.Therefore,this paper constructs an optimization model to minimize the number of fixtures.The constraints are set in the optimization model to ensure that the part deformation is within the surface profile tolerance.In addition,the assembly gap between two parts is also controlled.To conduct the optimization,this paper develops an improved particle swarm optimization(IPSO)algorithm by integrating the shrinkage factor and adaptive inertia weight.In the algorithm,particles are encoded according to the fixture position.Each dimension of the particle is assigned to a sub-region by constraining the optional position range of each fixture to improve the optimization efficiency.Finally,a case study on ship curved panel assembly is provided to prove that our method can optimize the number of fixtures while meeting the assembly quality requirements.This research proposes a method to optimize the number of fixtures,which can reduce the number of fixtures and achieve deformation control at the same time.

Novel subtype of obesity influencing the outcomes of sleeve gastrectomy:Familial aggregation of obesity

BACKGROUND Differences in the preoperative characteristics and weight loss outcomes after sleeve gastrectomy(SG)between patients with familial aggregation of obesity(FAO)and patients with sporadic obesity(SO)have not been elucidated.AIM To explore the impact of SG on weight loss and the alleviation of obesity-related comorbidities in individuals with FAO.METHODS A total of 193 patients with obesity who underwent SG were selected.Patients with FAO/SO were matched 1:1 by propensity score matching and were categorized into 4 groups based on the number of first-degree relatives with obesity(1 SO vs 1FAO,2SO vs 2FAO).The baseline characteristics,weight loss outcomes,prevalence of obesity-related comorbidities and incidence of major surgeryrelated complications were compared between groups.RESULTS We defined FAO as the presence of two or more first-degree relatives with obesity.Patients with FAO did not initially show significant differences in baseline data,short-term postoperative weight loss,or obesity-related comorbidities when compared to patients with SO preoperatively.However,distinctions between the two groups became evident at the two-year mark,with statistically significant differences in both percentage of total weight loss(P=0.006)and percentage of excess weight loss(P<0.001).The FAO group exhibited weaker remission of type 2 diabetes mellitus(T2DM)(P=0.031),hyperlipidemia(P=0.012),and non-alcoholic fatty liver disease(NAFLD)(P=0.003)as well as a lower incidence of acid reflux(P=0.038).CONCLUSION FAO patients is associated with decreased mid-to-long-term weight loss outcomes;the alleviation of T2DM,hyperlipidemia and NAFLD;and decreased incidence of acid reflux postoperatively.

Development of Fixture Layout Optimization for Thin-Walled Parts:A Review

An increasing number of researchers have researched fixture layout optimization for thin-walled part assembly during the past decades.However,few papers systematically review these researches.By analyzing existing literature,this paper summarizes the process of fixture layout optimization and the methods applied.The process of optimization is made up of optimization objective setting,assembly variation/deformation modeling,and fixture layout optimization.This paper makes a review of the fixture layout for thin-walled parts according to these three steps.First,two different kinds of optimization objectives are introduced.Researchers usually consider in-plane variations or out-of-plane deformations when designing objectives.Then,modeling methods for assembly variation and deformation are divided into two categories:Mechanism-based and data-based methods.Several common methods are discussed respectively.After that,optimization algorithms are reviewed systematically.There are two kinds of optimization algorithms:Traditional nonlinear programming and heuristic algorithms.Finally,discussions on the current situation are provided.The research direction of fixture layout optimization in the future is discussed from three aspects:Objective setting,improving modeling accuracy and optimization algorithms.Also,a new research point for fixture layout optimization is discussed.This paper systematically reviews the research on fixture layout optimization for thin-walled parts,and provides a reference for future research in this field.

Meter-Scale Thin-Walled Structure with Lattice Infill for Fuel Tank Supporting Component of Satellite:Multiscale Design and Experimental Verification

Lightweight thin-walled structures with lattice infill are widely desired in satellite for their high stiffness-to-weight ratio and superior buckling strength resulting fromthe sandwich effect.Such structures can be fabricated bymetallic additive manufacturing technique,such as selective laser melting(SLM).However,the maximum dimensions of actual structures are usually in a sub-meter scale,which results in restrictions on their appliance in aerospace and other fields.In this work,a meter-scale thin-walled structure with lattice infill is designed for the fuel tank supporting component of the satellite by integrating a self-supporting lattice into the thickness optimization of the thin-wall.The designed structure is fabricated by SLM of AlSi10Mg and cold metal transfer welding technique.Quasi-static mechanical tests and vibration tests are both conducted to verify the mechanical strength of the designed large-scale lattice thin-walled structure.The experimental results indicate that themeter-scale thin-walled structure with lattice infill could meet the dimension and lightweight requirements of most spacecrafts.

An electromagnetic semi-active dynamic vibration absorber for thin-walled workpiece vibration suppression in mirror milling

As critical components of aircraft skins and rocket fuel storage tank shells,large thin-walled workpieces are susceptible to vibration and deformation during machining due to their weak local stiffness.To address these challenges,we propose a novel tunable electromagnetic semi-active dynamic vibration absorber(ESADVA),which integrates with a magnetic suction follower to form a followed ESADVA(follow-ESADVA)for mirror milling.This system combines a tunable magnet oscillator with a follower,enabling real-time vibration absorption and condition feedback throughout the milling process.Additionally,the device supports self-sensing and frequency adjustment by providing feedback to a linear actuator,which alters the distance between magnets.This resolves the traditional issue of being unable to directly monitor vibration at the machining point due to space constraints and tool interference.The frequency shift characteristics and vibration absorption performance are comprehensively investigated.Theoretical and experimental results demonstrate that the prototyped follow-ESADVA achieves frequency synchronization with the milling tool,resulting in a vibration suppression rate of approximately 47.57%.Moreover,the roughness of the machined surface decreases by18.95%,significantly enhancing the surface quality.The results of this work pave the way for higher-quality machined surfaces and a more stable mirror milling process.

Functional Roux-en-Y Gastric Bypass (F-RYGB), with Preservation of Duodenal Access: Report of Two Revisional Cases of Sleeve Gastrectomy

Objective: This case report aimed to demonstrate a possible neuromuscular effect of Latarjet nerves transection or truncal vagotomy, in association with sleeve gastrectomy plus antrojejunostomy, in order to reproduce a Roux-en-Y gastric bypass (RYGB) mechanistic principles, in patients with previous Sleeve Gastrectomy (SG) who had had weight regain, with or without concomitant gastroesophageal reflux disease (GERD). Background: Sleeve gastrectomy (SG) is one of the most frequently performed bariatric operations worldwide. Nevertheless, weight regain and gastroesophageal reflux disease (GERD) have been consistently demonstrated, in association with this technique, which may require a revisional procedure. RYGB is an option in such a situation but, implies in gastrointestinal exclusions, which represents a shortcoming of this revision. Surpassing this inconvenient would be of great value for the patients. Methods: We describe herein two cases of SG revision for weight regain and GERD, with a follow-up of one year. Gastroesophageal reflux disease was evaluated by validated questionnaire, upper endoscopy, seriography, high resolution manometry (HRM) and impedance pHmetry (I-pHmetry), in the pre and postoperative periods. A re-Sleeve Gastrectomy with antrojejunal anastomosis was done in both cases, after informed consents. The Latarjet nerves were transected in one case, due to a bleeding in the left gastric vessels and a truncal vagotomy was required in the other, to appropriately treat an associated hiatal hernia. Results: In the postoperative evaluation it was observed a pyloric spasm in both cases, during seriography and endoscopy, kept until the one-year follow-up. There was unidirectional contrast flow to the gastrointestinal anastomosis, filling the jejunal limb, in radiologic contrast study. No contrast passed through the pylorus. Nonetheless, the duodenum was kept endoscopically accessible. In the one-year evaluation, weight loss was adequate and GERD resolution was obtained in both cases, confirmed by endoscopic and functional esophageal assessment, together with symptoms questionnaire. Conclusion: The association of Latarjet nerves sectioning or truncal vagotomy with re-sleeve gastrectomy plus gastrointestinal anastomosis (antrojejunal), in a revision for a failed sleeve, can represent a technical approach, to reproduce RYGB results, without exclusions and with duodenum endoscopic accessibility maintenance. It maybe could be applied for primary surgeries. Additional studies are necessary to confirm this hypothesis.

Numerical Analysis of Cold-Formed Thin-Walled Steel Short Columns with Pitting Corrosion during Bridge Construction

Pitting corrosion is harmful during bridge construction,which will lead to uneven roughness of steel surfaces and reduce the thickness of steel.Hence,the effect of pitting corrosion on the mechanical properties of cold-formed thin-walled steel stub columns is studied,and the empirical formulas are established through regression fitting to predict the ultimate load of web and flange under pitting corrosion.In detail,the failure modes and load-displacement curves of specimens with different locations,area ratios,and depths are obtained through a large number of non-linear finite element analysis.As for the specimens with pitting corrosion on the web,all the specimens are subject to local buckling failure,and the failure mode will not change with pitting corrosion,but the failure location will change with pitting corrosion location;the size,location,and area ratio of pitting corrosion have little influence on the ultimate load of cold-formed thin-walled steel short columns,but the loss rate of pitting corrosion section area has a greater impact on the ultimate bearing capacity.As for the specimen with flange pitting corrosion,the location and area ratio of pitting corrosion have less influence on the ultimate load of cold-formed thin-walled steel short columns,and the section area loss rate has greater influence on the ultimate bearing capacity;the impact of web pitting corrosion on the ultimate load is greater than that of flange pitting corrosion under the same condition of pitting corrosion section area.The prediction formulas of limit load which are suitable for pitting corrosion of web and flange are established,which can provide a reference for performance evaluation of corroded cold-formed thin-walled steel.

Association between operative position and postoperative nausea and vomiting in patients undergoing laparoscopic sleeve gastrectomy

BACKGROUND Bariatric surgery is one of the most effective ways to treat morbid obesity,and postoperative nausea and vomiting(PONV)is one of the common complications after bariatric surgery.At present,the mechanism of the high incidence of PONV after weight-loss surgery has not been clearly explained,and this study aims to investigate the effect of surgical position on PONV in patients undergoing bariatric surgery.AIM To explore the effect of the operative position during bariatric surgery on PONV.METHODS Data from obese patients,who underwent laparoscopic sleeve gastrectomy(LSG)in the authors’hospital between June 2020 and February 2022 were divided into 2 groups and retrospectively analyzed.Multivariable logistic regression analysis and the t-test were used to study the influence of operative position on PONV.RESULTS There were 15 cases of PONV in the supine split-leg group(incidence rate,50%)and 11 in the supine group(incidence rate,36.7%)(P=0.297).The mean operative duration in the supine split-leg group was 168.23±46.24 minutes and 140.60±32.256 minutes in the supine group(P<0.05).Multivariate analysis revealed that operative position was not an independent risk factor for PONV(odds ratio=1.192,95%confidence interval:0.376-3.778,P=0.766).CONCLUSION Operative position during LSG may affect PONV;however,the difference in the incidence of PONV was not statistically significant.Operative position should be carefully considered for obese patients before surgery.

Research on Sleeve Grouting Density Detection Based on the Impact Echo Method

Grouting defects are an inherent challenge in construction practices,exerting a considerable impact on the operational structural integrity of connections.This investigation employed the impact-echo technique for the detection of grouting anomalies within connections,enhancing its precision through the integration of wavelet packet energy principles for damage identification purposes.A series of grouting completeness assessments were meticulously conducted,taking into account variables such as the divergent material properties of the sleeves and the configuration of adjacent reinforcement.The findings revealed that:(i)the energy distribution for the highstrength concrete cohort predominantly occupied the frequency bands 42,44,45,and 47,whereas for other groups,it was concentrated within the 37 to 40 frequency band;(ii)the delineation of empty sleeves was effectively discernible by examining the wavelet packet energy ratios across the spectrum of frequencies,albeit distinguishing between sleeves with 50%and full grouting density proved challenging;and(iii)the wavelet packet energy analysis yielded variable detection outcomes contingent on the material attributes of the sleeves,demonstrating heightened sensitivity when applied to ultrahigh-performance concrete matrices and GFRP-reinforced steel bars.

Left lower lobe sleeve resection for the clear cell variant of pulmonary mucoepidermoid carcinoma:A case report

BACKGROUND Pulmonary mucoepidermoid carcinoma(PMEC)is a rare malignancy that arises from minor salivary glands within the tracheobronchial tree.The clear cell variant of PMEC is exceptionally uncommon and presents notable diagnostic challenges,primarily attributable to its morphological similarity to other tumors containing clear cells.CASE SUMMARY A 22-year-old male,formerly in good health,came in with a two-month duration of persistent cough and production of sputum.Subsequent imaging and bronchoscopy examinations revealed a 2 cm tumor in the distal left main bronchus,which resulted in complete atelectasis of the left lung.Further assessment via positron emission tomography/computed tomography scans and endoscopic biopsy confirmed the primary malignant nature of the tumor,charac-terized by clear cell morphology in most of the tumor cells.The patient underwent a left lower lobe sleeve resection accompanied by systematic mediastinal lymph node dissection.Molecular pathology analysis subsequently revealed a CRTC3-MAML2 gene fusion,leading to a definitive pathological diagnosis of the clear cell variant of PMEC,staged as T2N0M0.After surgery,the patient experienced a smooth recovery and exhibited no signs of recurrence during the one-and-a-half-year follow-up period.CONCLUSION This article describes an unusual case of a clear cell variant of PMEC characterized by the presence of a CRTC3-MAML2 gene fusion in a 22-year-old male.The patient underwent successful left lower lobe sleeve resection.This case underscores the distinctive challenges associated with diagnosing and treating this uncommon malignancy,underscoring the importance of precise diagnosis and personalized treatment strategies.

Sensitivity of springback and section deformation to process parameters in rotary draw bending of thin-walled rectangular H96 brass tube

In order to study the effects of the process parameters on springback and section deformation, a sensitivity analysis model was established based on the combination use of the multi-parameter sensitivity analysis method and the springback/section deformation prediction finite element model, and by using this model the sensitivities of the springback and the section deformation to process parameters were analyzed and compared. The results show that the most sensitive process conditions for springback angle are the boost speed and the pressure of pressure die, and the most sensitive process condition for section deformation is the number of cores. When the clamp force, the boost speed and the pressure of pressure die are utilized to control section deformation, the effect of these process parameters on springback should be considered. When the process parameters are mainly used to control springback, the effect of these process parameters on the section deformation should be always considered.

VIBRATION IN HIGH-SPEED MILLING OF THIN-WALLED COMPONENTS

To investigate the vibration principle in machining thin-walled components, a dynamic model for end milling of flexible structures is built based on considering the variations in the dynamic chip thickness and the differences between up-milling and down-milling. Two milling experiments verify the model. Experimental results show that the model can predict the milling force and displacements simultaneously in the dynamic milling process.

Infusa Sleeve导管血管内局部给药的实验研究

目的：评价ＩｎｆｕｓａＳｌｅｅｖｅ（ＩＳ）导管局部给药的可行性。方法：１３只家兔随机分成Ａ组（ｎ＝８）和Ｂ组（ｎ＝５），给药压力分别为６０７．９ｋＰａ（６个标准大气压）（Ａ组）和２０２．６ｋＰａ（２个标准大气压）（Ｂ组），用标准血管成形导管损伤腹主动脉下端后，经ＩＳ导管向腹主动脉下端球囊损伤处局部注入１ｍｌ放射性同位素锝标记的甲氧基异丁基异腈（９９ｍＴｃ－ＭＩＢＩ）注射液。术后３０分钟、６小时、２４小时分别处死动物后，取两组动物靶点血管（腹主动脉下端）、心、肝、骨骼肌、小肠、血液、非靶点血管（肺动脉）组织，用γ计数仪计数后称组织重量。结果：Ａ组和Ｂ组给药后３０分钟靶点血管局部的放射强度分别占给药总量的４９．２５０％和２２．０００％、分别是血液的４５倍和８倍、是非靶点血管的７０倍和１２倍。靶点血管局部放射强度Ａ组大于Ｂ组（Ｐ＜０．０５）。６小时和２４小时后靶点血管局部放射强度占给药总量的０．３４３％（Ａ组）和０．２５５％（Ａ组）。结论：ＩＳ导管可经血管局部靶向给药。ＩＳ导管局部导入的药物浓度呈压力依赖性。

Research and Design of Sleeve Detach and Reunion Drive Mechanism of Screw Melt Extruder Equipment

The design of sleeve detach and reunion drive device of screw melt ex- truder equipment was optimized, based on the present installation of hygraulic drive device to achieve the mechanical opening and closing of the sleeve, the dynamic model of the sleeve detach and reunion drive was theoretically measured, and it was verified that the device is simple to operate and convenient to maintain, thus it has great social values.

Warm bending mechanism of extrados and intrados of large diameter thin-walled CP-Ti tubes

In order to develop the warming bending technology of the large diameter thin-walled（LDTW） commercial pure titanium alloy CP-Ti tubes, the warm bending mechanism of the extrados and intrados of LDTW CP-Ti tubes was researched. By EBSD analysis and Vickers hardness test, the changes of microstructure and strength of the tubes at different bending temperatures of 293, 423 and 573 K, were analyzed. The results show： 1） The extrados of the bent tube deforms mainly by slip, along with few twinning, and the preferred orientation is similar to that of the initial tube; the intrados of the bent tube experiences compression deformation mainly by {1 012} tensile twinning, and the twinning makes the preferred orientation of wall materials change sharply. 2） The Vickers hardness values of both the extrados and intrados of the samples after bending increase greatly; the Vickers hardness values of the intrados are much higher than those of the extrados, and Vickers hardness values of the RD-TD planes are always higher than those of the RD-LD planes, which are related to the different deformation mechanisms.

Laparoscopic sleeve gastrectomy and gastroesophageal reflux

Bariatric surgery is the only effective procedure that provides long-term sustained weight loss. Sleeve gastrectomy(SG) has emerged over the last few years to be an ideal bariatric procedure because it has several advantages compared to more complex bariatric procedures,including avoiding an intestinal bypass. However,several published follow-up studies report an increased rate of gastroesophageal reflux(GERD) after a SG. GERD is described as either de novo or as being caused by aggravation of preexisting symptoms. However,the literature on this topic is ambivalent despite the potentially increased rate of GERDs that may occur after this common bariatric procedure. This article reviews the mechanisms responsible for GERD in obese subjects as well as the results after a SG with respect to GERD. Future directions for clinical research are discussed along with the current surgical options for morbidly obese patients with GERD and undergoing bariatric surgery.

Laparoscopic sleeve gastrectomy:More than a restrictive bariatric surgery procedure?

Sleeve gastrectomy(SG) is a restrictive bariatric surgery technique that was first used as part of restrictive horizontal gastrectomy in the original Scopinaro type biliopancreatic diversion. Its good results as a single technique have led to a rise in its use, and it is currently the second most performed technique worldwide. SG achieves clearly better results than other restrictive techniques and is comparable in some aspects to the Roux-en-Y gastric bypass, the current gold standard in bariatric surgery. These benefits have been associated with different pathophysiologic mechanisms unrelated to weight loss such as increased gastric emptying and intestinal transit, and activation of hormonal mechanisms such as increased GLP-1 hormone and decreased ghrelin. The aim of this review was to highlight the salient aspects of SG regarding its historical evolution, pathophysiologic mechanisms, main results, clinical applications and perioperative complications.

The success of sleeve gastrectomy in the management of metabolic syndrome and obesity

The rapid reversal of diabetes,hypertension,hyperlipidaemia and obesity by surgical means has challenged accepted doctrines regarding the management of metabolic syndrome.Sleeve gastrectomy,which developed initially as a preparatory procedure for biliopancreatic diversion with duodenal switch,has seen an exponential rise in popularity as an effective lone laparoscopic bariatric procedure.Superior excess weight loss,a low complication rate,and excellent food tolerance,combined with a short hospital stay,have made this the procedure of choice for patients and surgeons across the globe.High volume centres nurture the ongoing development of experienced and specialized teams,pathways and regimens.Optimum surgical outcomes allow minimization of metabolic syndrome,reducing cardiovascular and cerebrovascular risk.

Gastric remnant twist in the immediate post-operative period following laparoscopic sleeve gastrectomy

Twist of stomach remnant post sleeve gastrectomy is a rare entity and difficult to diagnose pre-operatively. We are reporting a case of gastric volvulus post laparoscopic sleeve gastrectomy, which was managed conservatively. A 38-year-old lady with a body mass index of 54 underwent laparoscopic sleeve gastrectomy. Sleeve gastrectomy was performed over a 32 French bougie using Endo-GIA tri-stapler. On post-operative day 1, patient had nausea and non-bilious vomiting. An upper gastrointestinal gastrografin study on postoperative days 1 and 2 revealed collection of contrast in the fundic area of stomach with poor flow distally, and she vomited gastrograffin immediately post procedure. With the suspicion of a stricture in the mid stomach as the cause, the patient was taken back for a exploratory laparoscopy and intra-operative endoscopy. We found a twist in the gastric tube which was too tight for the endoscope to pass through. This was managed conservatively with a long stent to keep the gastric tube straight and patent. The stent was discontinued in 7 d and the patient did well. In laparoscopic sleeve gastrectomy the stomach is converted into a tube and is devoid of its supports. If the staples fired are not aligned appropriately, it can predispose this stomach tube to undergo torsion along its long axis. Such a twist can be avoided by properly aligning the staples and by placing tacking sutures to the omentum and new stomach tube. This twist is a functional obstruction rather than a stricture; thus, it can be managed by endoscopy and stent placement.

Current status of endoscopic sleeve gastroplasty: An opinion review

Bariatric surgeries have been demonstrated to be safe and effective treatment options for morbid obesity patients, but operative risks and high health care costs limit their clinical application. Endoscopic bariatric therapies are emerging as valuable alternatives for patients with doubts about bariatric surgery or ineligible for it. Endoscopic sleeve gastroplasty(ESG), a relatively novel technique of endoscopic bariatric therapies, has gained standing in the past few years. The safety, feasibility, repeatability, and potential for reversibility of ESG have been proven by multicenter studies. Compared to other weight loss strategies, current evidence demonstrates that ESG offers satisfactory efficacy in weight loss. Even though it is inferior to laparoscopic sleeve gastrectomy, it has lower risks of adverse events than surgical interventions and intragastric balloon within oneyear follow-up. Furthermore, ESG may be the ideal weight control strategy for patients who have poor adherence to behavioral interventions. Even so, trends in decreased weight loss effect over time, post-procedure weight regain, postprocedure gut hormone alteration, and possible effects of race and ethnicity on ESG still remain undetermined due to very limited reports and very short followups. Further clinical trials are required to validate and answer these questions.