A strategy for strengthening chaotic mixing of dual shaft eccentric mixers by changing non-Newtonian fluids kinetic energy distribution

Efficiently modulating the velocity distribution and flow pattern of non-Newtonian fluids is a critical challenge in the context of dual shaft eccentric mixers for process intensification,posing a significant barrier for the existing technologies.Accordingly,this work reports a convenient strategy that changes the kinetic energy to controllably regulate the flow patterns from radial flow to axial flow.Results showed that the desired velocity distribution and flow patterns could be effectively obtained by varying the number and structure of baffles to change kinetic energy,and a more uniform velocity distribution,which could not be reached normally in standard baffle dual shaft mixers,was easily obtained.Furthermore,a comparative analysis of velocity and shear rate distributions is employed to elucidate the mechanism behind the generation of flow patterns in various dual-shaft eccentric mixers.Importantly,there is little difference in the power number of the laminar flow at the same Reynolds number,meaning that the baffle type has no effect on the power consumption,while the power number of both unbaffle and U-shaped baffle mixing systems decreases compared with the standard baffle mixing system in the transition flow.Finally,at the same rotational condition,the dimensionless mixing time of the U-shaped baffle mixing system is 15.3%and 7.9%shorter than that of the standard baffle and the unbaffle mixing system,respectively,which shows the advantage of the U-shaped baffle in stirring rate.

Lightweight Res-Connection Multi-Branch Network for Highly Accurate Crowd Counting and Localization

Crowd counting is a promising hotspot of computer vision involving crowd intelligence analysis,achieving tremendous success recently with the development of deep learning.However,there have been stillmany challenges including crowd multi-scale variations and high network complexity,etc.To tackle these issues,a lightweight Resconnection multi-branch network(LRMBNet)for highly accurate crowd counting and localization is proposed.Specifically,using improved ShuffleNet V2 as the backbone,a lightweight shallow extractor has been designed by employing the channel compression mechanism to reduce enormously the number of network parameters.A light multi-branch structure with different expansion rate convolutions is demonstrated to extract multi-scale features and enlarged receptive fields,where the information transmission and fusion of diverse scale features is enhanced via residual concatenation.In addition,a compound loss function is introduced for training themethod to improve global context information correlation.The proposed method is evaluated on the SHHA,SHHB,UCF-QNRF and UCF_CC_50 public datasets.The accuracy is better than those of many advanced approaches,while the number of parameters is smaller.The experimental results show that the proposed method achieves a good tradeoff between the complexity and accuracy of crowd counting,indicating a lightweight and high-precision method for crowd counting.

Theoretical and Experimental Research of High-Static-Low Dynamic Torsional Vibration Isolator for Ship Shafting

High-static-low-dynamic stiffness (HSLDS) vibration isolators have been demonstrated to be an effective means of attenuating low-frequency vibrations, and may be utilized for ship shafting applications to mitigate torsional vibration. This paper presents the construction of a highly compact HSLDS torsional vibration isolator by connecting positive and negative stiffness components in paral lel. Based on mechanical model analysis, the restoring torque of negative stiffness components is de rived from their springs and connecting rods, while that of positive stiffness components is obtained through their circular section flexible rods. The quasizero stiffness characteristics of the HSLDS iso lator are achieved through a combination of static structural simulation and experimental test. The tor sional vibration isolation performance is assessed by means of numerical simulation and theory analy sis. Finally, the frequency-sweep vibration test is conducted. The test results indicate that the HSLDS torsional vibration isolator exhibits superior low-frequency isolation performance compared to its linear counterpart, rendering it a promising solution for mitigating low-frequency torsional vi bration in ship shafting.

A Multiscale Reliability-Based Design Optimization Method for Carbon-Fiber-Reinforced Composite Drive Shafts

Carbon fiber composites,characterized by their high specific strength and low weight,are becoming increasingly crucial in automotive lightweighting.However,current research primarily emphasizes layer count and orientation,often neglecting the potential of microstructural design,constraints in the layup process,and performance reliability.This study,therefore,introduces a multiscale reliability-based design optimization method for carbon fiber-reinforced plastic(CFRP)drive shafts.Initially,parametric modeling of the microscale cell was performed,and its elastic performance parameters were predicted using two homogenization methods,examining the impact of fluctuations in microscale cell parameters on composite material performance.A finite element model of the CFRP drive shaft was then constructed,achieving parameter transfer between microscale and macroscale through Python programming.This enabled an investigation into the influence of both micro and macro design parameters on the CFRP drive shaft’s performance.The Multi-Objective Particle Swarm Optimization(MOPSO)algorithm was enhanced for particle generation and updating strategies,facilitating the resolution of multi-objective reliability optimization problems,including composite material layup process constraints.Case studies demonstrated that this approach leads to over 30%weight reduction in CFRP drive shafts compared to metallic counterparts while satisfying reliability requirements and offering insights for the lightweight design of other vehicle components.

Early Treatment Outcome of Humeral Shaft Fracture Non-Union in Adults: Comparative Study of Plating versus Interlocking Nailing

Background: Fractures of humeral shaft in adults are common injuries. Humeral shafts non-union either from late presentation after initial treatment by traditional bone setters or failed non-operative orthodox care is a major problem in this part of the world. This non-union is a major treatment challenge with increased cost of care and morbidity in this part of the world. Humeral shaft non-union can be treated with locked intra-medullary nailing (LIMN) or dynamic compression plating (DCP). Study on comparison of these methods of fixation in this part of the world is scarce in literature search, hence the reason for this study. Objective: The objectives of this study are: (1) to compare early clinical outcome following fixation of humeral shaft fracture nonunion with DCP versus LIMN;(2) to compare the time of radiologic fracture union of DCP with LIMN;(3) to compare complications following fixation of humeral shaft fracture nonunion with DCP versus LIMN. Patients and Methods: This was a randomized control study done for 2 years in which fifty adult patients with humeral shaft non-union were recruited. The patients were grouped into 2 (P = DCP & N = LIMN). Forty five of the patients completed the follow up periods of the study and then analyzed. The P group had ORIF with DCP while the N group had ORIF with LIMN. Both groups had grafting with cancellous bones. Each patient was followed up for a period of 6 months at the time which radiographic union is expected. Any patient without clinical and/or radiographic evidence of union after six months of surgery was diagnosed as having recurrent non-union. The data generated was analyzed using SPSS Version 23. The results were presented in charts and tables. The paired t-test was used while considering p value Result: Forty five patients completed follow up. There was a male preponderance (4:1), right humerus predominated (3:2). Motor vehicular accidents were the commonest cause of the fractures (62%). Most non-union fractures occurred at the level of the middle 3rd of the humeral shaft (60%). Failed TBS treatment was the commonest indication for the osteosynthesis (71%). More patients had plating (53%) compared to 47% who had LIMN. Most patients (93.4%) had union between 3 to 6 months irrespective of fixation type with no significant statistical difference between the union rate of DCP and LIMN (p value 0.06) with similar functional outcome and complication rates irrespective of the type of fixation. Conclusion: This study showed that the success rates in term of fracture union, outcome functional grades and complication rates were not directly dependent on the types of the fixation: plating or locked intra-medullary nailing.

A hybrid ventilation scheme applied to bidirectional excavation tunnel construction with a long inclined shaft

The breakage and bending of ducts result in a difficulty to cope with ventilation issues in bidirectional excavation tunnels with a long inclined shaft using a single ventilation method based on ducts.To discuss the hybrid ventilation system applied in bidirectional excavation tunnels with a long inclined shaft,this study has established a full-scale computational fluid dynamics model based on field tests,the Poly-Hexcore method,and the sliding mesh technique.The distribution of wind speed,temperature field,and CO in the tunnel are taken as indices to compare the ventilation efficiency of three ventilation systems(duct,duct-ventilation shaft,duct–ventilated shaft-axial fan).The results show that the hybrid ventilation scheme based on duct-ventilation shaft–axial fan performs the best among the three ventilation systems.Compared to the duct,the wind speed and cooling rate in the tunnel are enhanced by 7.5%–30.6%and 14.1%–17.7%,respectively,for the duct-vent shaft-axial fan condition,and the volume fractions of CO are reduced by 26.9%–73.9%.This contributes to the effective design of combined ventilation for bidirectional excavation tunnels with an inclined shaft,ultimately improving the air quality within the tunnel.

Clinical effect of operative vs nonoperative treatment on humeral shaft fractures:Systematic review and meta-analysis of clinical trials

BACKGROUND Whether operation is superior to non-operation for humeral shaft fracture remains debatable.We hypothesized that operation could decrease the nonunion and reintervention rates and increase the functional outcomes.AIM To compare the clinical efficacy between operative and nonoperative approaches for humeral shaft fractures.METHODS We searched the PubMed,Web of Science,ScienceDirect,and Cochrane databases from 1990 to December 2023 for clinical trials and cohort studies comparing the effects of operative and conservative methods on humeral shaft fractures.Two investigators independently extracted data from the eligible studies,and the other two assessed the methodological quality of each study.The quality of the included studies was assessed using the Cochrane risk bias or Newcastle-Ottawa Scale.The nonunion,reintervention and the overall complications and functional scores were pooled and analyzed using Review Manager software(version 5.3).RESULTS A total of four randomized control trials and 13 cohort studies were included,with 1285 and 1346 patients in the operative and nonoperative groups,respectively.Patients in the operative group were treated with a plate or nail,whereas those in the conservative group were managed with splint or functional bracing.Four studies were assessed as having a high risk of bias,and the other 13 were of a low risk of bias according to the Newcastle-Ottawa Scale or Cochrane risk bias tool.The operative group had a significantly decreased rate of nonunion[odds ratio(OR)0.30;95%CI:0.23 to 0.40,reintervention(OR:0.33;95%CI:0.24 to 0.47),and overall complications(OR:0.62;95%CI:0.49 to 0.78)].The pooled effect of the Disabilities of Arm,Shoulder,and Hand score showed a significant difference at 3[mean difference(MD)-8.26;95%CI:-13.60 to-2.92],6(MD:-6.72;95%CI:-11.34 to-2.10),and 12 months(MD:-2.55;95%CI:-4.36 to-0.74).The pooled effect of Visual Analog Scale scores and the Constant-Murley score did not significantly differ between the two groups.CONCLUSION This systematic review and meta-analysis revealed a trend of rapid functional recovery and decreased rates of nonunion and reintervention after operation for humeral shaft fracture compared to conservative treatment.

Functional Outcomes of Adult Tibia Shaft Fractures Treated with Solid Intramedullary Nails versus Hollow Nails: A Systematic Review

Introduction: The management of fractures of the tibia shaft is an important aspect of orthopaedic care, and the selection of the surgical method for fixation can substantially impact patient outcomes. The current review aims to compare the outcomes of adult tibia fractures treated with solid nails to those treated with hollow nails. Methods: A search on Scopus, PubMed, and Cochrane Library, using three keywords (Outcome, Tibia shaft fractures, Nail) was conducted in April 2023. Results were compiled and two independent reviewers screened and selected eligible articles After removing duplicates, titles and abstracts were read to exclude ineligible studies. Full-text articles of the remaining papers were read to select eligible studies which were further critically appraised to ascertain their methodological quality. The data extracted from the selected papers were synthesized using a combination of pooling of results, tests of statistical difference (t-test and chi-square) and narrative synthesis methods. Results: A total of 2295 articles were obtained from the databases and citation searching. A total of 9 papers were identified as eligible and included in the review. Findings revealed that there is no statistical difference in the outcomes of tibia fractures treated with either solid or hollow nail groups such as duration of surgery (p = 0.541), rate of delayed and non-union (p = 0.342), and rate of surgical site infections (p = 0.395). Conclusion: Intramedullary nailing of tibia shaft fractures with either solid or hollow nails have similar functional outcomes.

Multi-Branch Fault Line Location Method Based on Time Difference Matrix Fitting

The distribution network exhibits complex structural characteristics,which makes fault localization a challenging task.Especially when a branch of the multi-branch distribution network fails,the traditional multi-branch fault location algorithm makes it difficult to meet the demands of high-precision fault localization in the multi-branch distribution network system.In this paper,the multi-branch mainline is decomposed into single branch lines,transforming the complex multi-branch fault location problem into a double-ended fault location problem.Based on the different transmission characteristics of the fault-traveling wave in fault lines and non-fault lines,the endpoint reference time difference matrix S and the fault time difference matrix G were established.The time variation rule of the fault-traveling wave arriving at each endpoint before and after a fault was comprehensively utilized.To realize the fault segment location,the least square method was introduced.It was used to find the first-order fitting relation that satisfies the matching relationship between the corresponding row vector and the first-order function in the two matrices,to realize the fault segment location.Then,the time difference matrix is used to determine the traveling wave velocity,which,combined with the double-ended traveling wave location,enables accurate fault location.

Beyond p-y method:A review of artificial intelligence approaches for predicting lateral capacity of drilled shafts in clayey soils

In 2023,pivotal advancements in artificial intelligence(AI)have significantly experienced.With that in mind,traditional methodologies,notably the p-y approach,have struggled to accurately model the complex,nonlinear soil-structure interactions of laterally loaded large-diameter drilled shafts.This study undertakes a rigorous evaluation of machine learning(ML)and deep learning(DL)techniques,offering a comprehensive review of their application in addressing this geotechnical challenge.A thorough review and comparative analysis have been carried out to investigate various AI models such as artificial neural networks(ANNs),relevance vector machines(RVMs),and least squares support vector machines(LSSVMs).It was found that despite ML approaches outperforming classic methods in predicting the lateral behavior of piles,their‘black box'nature and reliance only on a data-driven approach made their results showcase statistical robustness rather than clear geotechnical insights,a fact underscored by the mathematical equations derived from these studies.Furthermore,the research identified a gap in the availability of drilled shaft datasets,limiting the extendibility of current findings to large-diameter piles.An extensive dataset,compiled from a series of lateral loading tests on free-head drilled shaft with varying properties and geometries,was introduced to bridge this gap.The paper concluded with a direction for future research,proposes the integration of physics-informed neural networks(PINNs),combining data-driven models with fundamental geotechnical principles to improve both the interpretability and predictive accuracy of AI applications in geotechnical engineering,marking a novel contribution to the field.

Short-term warning and integrity monitoring algorithm for coal mine shaft safety

A new short-term warning and integrity monitoring algorithm was proposed for coal mine shaft safety. The Kalman filter (KF) model was used to extract real global positioning system (GPS) kinematic deformation information. The short-term warning model was built by using the two-side cumulative sum (CUSUM) test, which further improves the warning system reliability. Availability (the minimum warning deformation, MWD), false alarm rate (the average run length, ARL), missed rate (the warning delay, WD) and the relationships among them were analyzed and the method choosing warning parameters is given. A test of a deformation simulation platform shows that the warning algorithm can be effectively used for steep deformation warning. A field experiment of the Malan mine shaft in Shanxi coal area illustrates that the proposed algorithm can detect small dynamic changes and the corresponding occurring time. At given warning thresholds (MWD is 15 mm and ARL is 1000),the detected deformations of two consecutive days’ deformation sequences with the algorithm occur at the 705th epoch (705 s) and the 517th epoch (517 s), respectively.

Multi-branched carbazole derivatives for two-photon absorption and two-photon excited fluorescence

Carbazole-core multi-branched chromophores 9-ethyl- 3, 6-bis （ 2- { 4- [ 5- （4-tert-butyl-phenyl） - [ 1, 3, 4 ] oxadiazol-2-yl ] - phenyl }-vinyl） -carbazole（3） and 9-ethyl-3-（ 2- {4-[ 5-（4-tert-butyl- phenyl） -[ 1, 3, 4 ] oxadiazol-2-yl ] -phenyl }-vinyl ） -carbazole （ 2 ） are synthesized through Wittig reaction and characterized by nuclear magnetic resonance（NMR）and infrared（IR）. The two- photon absorption properties of chromophores are investigated. These chromophores exhibit large two-photon absorption crosssections and strong blue two-photon excited fluorescence. The cooperative enhancement of two-photon absorption（TPA） in the multi-branched structures is observed. This enhancement is partly attributed to the electronic coupling between the branches. The electronic push-pull structures in the arm and their cooperative effects help the extended charge transfer for TPA.

Smoke distribution in naturally ventilated urban transportation tunnels with multiple shafts

The smoke spreading law of urban transportation tunnels with multiple shafts under natural ventilation is studied.A full-scale burning experiment is conducted in an actual tunnel.The study shows that smoke temperatures below the tunnel ceiling reduce rapidly along the longitudinal towards the tunnel exits. A noticeable temperature stratification is observed near the fire source.Most fire smoke is exhausted out of the shafts while the number of the smoke shafts in the downstream is more than that in the upstream.Large eddy simulation LES based on computational fluid dynamics CFD is carried out using the fire dynamics simulator FDS software with parallel processing in which the grid size of the fire-domain is set to be 0.083 m.The simulation results of temperatures under the ceiling the smoke fronts and the shafts＇smoke exhaust or air supply agree reasonably with the experimental data. Further simulations indicate that the decreasing ambient temperature or shaft spacing might reduce smoke temperatures under the tunnel ceiling and increase mass flow rates out of the shafts.This study provides technical scientific evidence and supports for the design and construction of such kinds of tunnels.

NUMERICAL ANALYSIS ON INCREASE OF SECTIONAL STRESS OF A SHAFT WITH RUB－IMPACT CONDITION

The numerical analysis on a shaft with rub-impact condition is done by using the finite difference method. The bending modes and the moment yaring along the shaft are described,to reveal the in crease pattern of sectional stress of the shaft. The result obtained in this paper can be used in explaining the phenomena of many breaking sections appeared in destructive failures of actual rotating machinery.

Study of LDBPs Shaft Skin Friction for Piles in Cohesiove Soils

The methodology of predicting pile shaft skin ultimate friction has been studied in a systematic way. In the light of that, the analysis of the pile shaft resistance for bored and cast in situ piles in cohesive soils was carried out thoroughly in the basis of field performance data of 10 fully instrumented large diameter bored piles (LDBPs) used as the bridge foundation. The undrained strength index μ in term of cohesive soils was brought forward in allusion to the cohesive soils in the consistence plastic state, and can effectively combine the friction angle and the cohesion of cohesive soils in undrained condition. And that the classical ' α method' was modified much in effect to predict the pile shaft skin friction of LDBPs in cohesive soils. Furthermore, the approach of standard penetration test (SPT) N value used to estimate the pile shaft skin ultimate friction was analyzed, and the calculating formulae were established for LDBPs in clay and silt clay respectively.

一种新的转子轴端密封结构设计--阶梯式

本文简要介绍目前密炼机转子常用的几种轴端密封形式及其优缺点,探讨一种新的转子轴端密封结构设计——阶梯式,该结构可以在一定程度上改善密封效果,减少维护更换次数。

表面淬火技术在液压支架中的研究与应用

随着液压支架设计与制造技术的日益发展,对液压支架使用寿命要求越来越高。作为液压支架动作(摩擦)的核心部位,立柱的活柱杆头、外缸底表面及顶梁与掩护梁的铰接轴、掩护梁与连杆的铰接轴、连杆与底座的铰接轴等几个摩擦部位是影响液压支架使用寿命最核心的部位。根据以往的经验,这几处动作(摩擦)部位的零部件通常损坏较严重,难以修复。因此,提高这些零件摩擦部位的寿命对液压支架整体寿命的提高有很重要的意义。

减速器推力轴承定位偏差影响轴系径向跳动异常分析

双螺杆挤出机是一种常用的塑料加工设备,在双螺杆挤出机减速器的生产制造过程中,出现了输出轴径向误差检测异常现象。输出轴转动两周,百分表指针检测数值从零点回到零点。本文从推力轴承结构方面对其进行分析,详细介绍了出现此种情况的原因及解决此问题的方案。

微型顶管钢制井筒内力理论解及其壁厚研究

针对微型顶管应用面逐步扩大的背景及趋势,为实现钢筒量化设计及科学施工,研究钢筒受力的理论解。钢制井筒所受外力拆解为顶进时的土反力及主动土压力两部分,分析数值模拟所得土反力大小及分布规律,借鉴钢筋混凝土沉井经验归纳出钢筒内力理论解答,进而讨论钢筒壁厚的影响因素。结果表明,钢筒所受土反力水平向按余弦函数分布,竖向按指数分布,分布状态均与所处地层特性相关;钢筒所需壁厚与顶力大小、钢筒内径、管道埋深正相关,与土体m值反相关;可通过加固后靠背土体或采用触变泥浆减小顶力等方法控制钢筒壁厚在合理范围内。

Simulation Study on Reinforcing Overburden to Prevent and Cure the Rupture of Shaft Lining

For preventing and curing the rupture disaster of shaft lining effectively, according to the additional force theory of shaft lining fracture, more than forty tests were carried out on the large scale test rig on the basis of simulating theory. The influence of the position of aquifer, the reinforcing scope of aquifer, reinforcing distance and the strength of grouting cemented mixture on the value and variation law of the axial additional force on shaft lining is studied. The relationships between the reinforcing parameters and the axial additional force on shaft lining are obtained, which provides the theoretic foundation and construction design parameters for the method of reinforcing strata by grouting to prevent and cure tbe rupture disaster of shart lining.