Using Circular Economics Strategies to Manage Tourism on Remote Islands:A SMART Approach

Circular economics theory offers destination managers of remote islands a solution-oriented approach to environmental sustainability. This paper examines the practical benefits of this theory that will support the development of a circular economy regarding sustainable island tourism (SIT). The aim of this paper is to inform discussions regarding the feasibility of applying a practice theory that emphasises changes in the behaviours across three segments, visitors, residents, and enterprises using SMART technologies. To achieve this objective, a SMART indicator system (SIS) was used to identify current practices that would support a circular economy (CE). The key innovation of this study is the creation of a proposed framework that may inform best practices for SIT in the future. The findings highlight the potential opportunity of evidenced-based planning to deliver a circular economy strategy (CES) for remote islands in the future. These insights can potentially impact the way that local authorities and destination managers approach the planning of tourism for six islands along the west coast of Ireland.

Wet and Dry Tribological Behaviors of Circular Islandic Protrusion Patterns on M2 Steel Discs under Spinning Condition

Under spinning conditions, lubricant on islandic spot patterned M2 steel disc experiences centrifugal and tangential force components. Depending upon the relative position of the spots and the flow of lubricant, accumulation of lubricant in front of patterned islandic spots creates thrusting to mating part and subsequently reduces contact between the mating couple. Whilst wear debris is likely to be spun off the plateau of the spots to their neighbouring valleys so as to reduce wear. Hence, it gives favorable tribological characteristics. Aiming at verifying such mechanisms, studies were performed on M2 steel disc specimens slid with ASSAB 17 tool steel pin. The M2 steel disc specimens were respectively （i） machined with non-patterned （NP）, （ii） etched to produce in-lined （INE） islandic patterns, and （iii） etched to produce staggered （STE） islandic spot patterns. Results indicated that the INE patterned discs gave most favorable wear characteristics, the NP of the worse characteristics whilst the STE ranged in the middle. However, the actual contact mechanism leads to the descending sequence of favorable friction behaviors nominally as： NP, INE and STE.

Trapping Mechanism for Long Waves over Circular Islands with Power Function Profiles

Long waves such as tsunamis can be trapped by islands due to wave refraction,and these trapped waves will cause huge damage even in the sheltered shoreline of the island.That all waves propagating into the topography and finally reaching the coastline are called perfect trapped modes,while any waves escaping from the topography are called leaky modes.Whether these long waves can be trapped is dependent on the depth profile of the island.This paper presents analytic solutions of the ray path for waves propagating into the circular island with power function profiles.Wave height distributions over the island are further investigated based on the principia that crowded rays correspond to large wave height and sparse rays correspond to small wave height.The trapped mechanism for water waves over the island is revealed based on their ray paths.Furthermore,the perfectly trapped criterion is derived,that is,when the slope gradient at the topography toe is greater than twice the ratio of the water depth to the radial distances,all wave rays propagating on the island will finally reach the coastline,and the waves are perfectly trapped.

MORPHOLOGICAL VARIATIONS OF INITIAL DEPRESSION ARISEN FROM CRUSTAL MOVEMENT DURING QUATERNARY ON SEVERAL ISLANDS IN THE RYUKYUS, JAPAN

interest is to make clear the occurring mechanism of the init(?) (?)ion on the limestone terrain I have been investigating (?) (?)ssions on several islands over the Ryukyu islands under the hum(?) (?) zone.The Ryukyus are composod of more than 70 isiands with (?) (?) reef limestone There are geomor(?)hological feature of var karstic initial depressions on each isiand affeeted by diff(?) crustal movement with (?)eated aplifted dro(?)ed

Ultimate flexural strength of normal section of FRP-confined RC circular columns

Numerical analysis is carried out to study the sectional properties of the fiber-reinforced polymer（FRP）-confined reinforced concrete（RC）circular columns. The axial load ratio, the FRP confinement ratio and the longitudinal reinforcement characteristic value are the three main parameters that can influence the neutral axis depth when concrete compression strain reaches an ultimate value. The formula for computing the central angle θ, corresponding to the compression zone, is established according to the data regression of the numerical analysis results. The numerical analysis results demonstrate that the concrete stress enhancement from transverse confinement and strain hardening of the longitudinal reinforcement can cause a much greater flexural strength than that defined by the design code. Based on the analytical studies and the test results of 36 large scale columns, the formula to calculate the flexural strength when columns fail under seismic loading is proposed, and the calculated results agree well with the test results. Finally, parametric studies are conducted on a typical column with different axial load ratios, longitudinal reinforcement characteristic value and FRP confinement ratios. Analysis of the results shows that the calculated flexural strength can be increased by 50% compared to that of unconfined columns defined by the code.

MAGNETOHYDRODYNAMIC PIPE FLOW IN DUCTS WITH PARTIAL CIRCULAR RING CROSS SECTION AND ANNULAR CROSS SECTION

In this paper we use the Green function method to solve the problem of steady one dimensional flow of an incompressible viscous, electrically conducting fluid through a pipe with partial circular ring cross sec- tion and one with annular cross section, in the presence of an applied transverse uniform magnetic field, We ob- tain analytic solutions and carry out some numerical calculations of the velocity distribution and induced magnet- ic field.

Ultimate Load Capacity and Reinforcement of Circular-Hollow-Section N-Joint

Experimental research and numerical analysis were applied to study the ultimate load capacity(ULC) and reinforcement of circular-hollow-section N-joint.Four specimens were tested under static load.The ULC of each specimen was obtained and the detailed failure conditions were discussed.Based on the results, both welding a plate on the chord member and filling concrete in the chord member are effective to reinforce the N-joint, but it is suggested that these two methods should not be applied simultaneously.Mo...

HYBRID PERTURBATION-GALERKIN SOLUTION OF THE FLOW IN A CIRCULAR CROSS-SECTION TUBE WITH CONSTRICTION

Using hybrid perturbatin_Galerkin technique,a crcular cross_section tube model with sinusoidal wall is studied.This technique can remove the limitation of small parameters for perturbation and the difficulty of selecting good coordinate functions about Galerkin technique.The effects caused by the boundary conditions and the Reynolds number on the flow were discussed.The position of the separate and reattachment points was obtained.The tendency of the variation about the shear stress on the wall and friction factor along the axis direction were also analyzed.The results at a small parameter have good agreements with the perturbation ones.

Experimental and Numerical Investigation of the Performance of Turbulent Heat Transfer in Tubes with Different Cross-Sectioned Wire Coils

The thermal-hydraulic performance of plain tubes with and without wire coils in turbulent regimes is investigated experimentally and numerically.The effects of wire coil distribution(circular cross section)within the tube were explored experimentally,and water was employed as the working fluid.The numerical simulation was carried out using software programmer ANSYS Fluent 2019 R3 using the finite-volume approach.In the turbulent regime,six cross-sectionedwire coilswere analyzed,including:circular,rectangular,hexagonal,square,star shape,and triangle.The utilization of a tube with a wire coil has been shown to increase heat transfer rate and pump consumption.The results indicate a high level of concurrence,as the deviations are all below 8%.Compared with plain tube,the wire coils,according to the arrangement(TWD),gave the best PEC.The heat transfer enhancement ability of different cross sections follows the following order:StCS>RCS>HCS>SqCS>CCS>TCS.Also,the sequence of pump consumption for each cross section is as follows:RCS>StCS>SqCS>HCS>CCS>TCS.

Soft-sediment deformation structures related to volcanic earthquakes of the Lower Cretaceous Qingshan Group in Lingshan Island, Shandong Province, East China

The study on soft-sediment deformation structures(SSDS) of Lingshan Island has been one of the hot topics of sedimentology researches in China in recent years,and SSDS developed in turbidite system in the Laiyang Group are widely known by domestic researchers.However,few studies were conducted on the SSDS in fan delta system in the Qingshan Group,Lingshan Island.This study analyzes the classification and characteristics of SSDS especially their lithofacies association and tithologic characteristics through field outcrops investigation and thin section analysis as well.A conclusion was acquired that the paleoenvironment was a fan delta system with occurrence of several volcanic eruptions,where the water became gradually shallower.The SSDS types in the Qingshan Group includes load and flame structure,ball and pillow structure,waterescape structure,hydroplastic deformation structure,plastic sandstone breccia structure,volcanic drop stone and V-shaped ground fissure mainly caused by volcanic earthquakes of three types:(1)seismic waves,(2)gravity and inertia effect of pyroclastic flows,(3)instant differential air pressure;which is different from slumping and tectonic earthquakes occurred in the Laiyang Group.In addition,with the lithofacies association analysis between pyroclastic flow and SSDS beds,a distribution model of SSDS related to volcanic earthquakes can be established:SSDS types changed gradually with their distance further away from the volcanic activity core.Brittle deformation which was common in the proximal zone disappeared gradually;liquefied and plastic SSDS continued to dominate in the medial zone;and slightly liquefied SSDS were developed in the distal zone.Meanwhile,the scale and size of SSDS is negatively correlated with the distance of SSDS depositional locations from the volcanic vent.

Experimental research on mechanical properties of prestressed truss concrete composite beam encased with circular steel tube

Tests of 4 simply supported unbonded prestressed truss concrete composite beams encased with circular steel tube were carried out. It is found that the ratio of the stress increment of the unbonded tendon to that of the tensile steel tube is 0.252 during the using stage,and the average crack space of beams depends on the ratio of the sum of the bottom chord steel tube's outside diameter and the secondary bottom chord steel tube's section area to the effective tensile concrete area. The coefficient of uneven crack distribution is 1.68 and the formula for the calculation of crack width is established. Test results indicate that the ultimate stress increment of unbonded tendon in the beams decreases in linearity with the increase of the composite reinforcement index β0. The pure bending region of beams accords with the plane section assumption from loading to failure. The calculation formula of ultimate stress increment of the unbonded tendon and the method to calculate the bearing capacity of normal section of beams have been presented. Besides,the method to calculate the stiffness of this sort of beams is brought forward as well.

平面内弯矩作用下T形圆管相贯节点热点应力分布

本文针对平面内弯矩作用下的T形圆管相贯节点焊缝处热点应力分布开展研究.利用径向拉伸法建立了T形圆管相贯节点的有限元网格模型,对热点应力分析结果的可靠性进行了网格密度分析和试验对比分析,提出了满足计算精度要求的基本密度网格.通过无量纲几何参数分析归纳了热点应力沿相贯线的环向分布规律及几何参数影响规律,发现了冠点波峰分裂现象及分裂过程中波峰曲线的三种变化形态,在此基础上提出了采用以π为周期的系数来修正冠点曲线形状的波形修正方法及分布曲线参数公式.与伦敦大学学院(University College London,UCL)两位学者的公式和试验数据进行对比分析,结果表明本文公式具有更简洁的表达形式和更高的精度.

硬梁包水电站方变圆大断面隧洞开挖技术

硬梁包水电站引水隧洞进口方变圆大断面洞室开挖通过先进行安全治理、锁口支护、超前预支护等措施后再进入洞段施工,先进行导洞开挖,再利用导洞开挖取得的技术参数和其所揭示的实际地质情况完成扩挖和分段分层开挖,施工时大量采用光爆和预裂爆破技术与工艺,抓住质量关键并严格过程控制,有效地保证了工程控制目标,效果明显,所取得的经验可为类似工程施工借鉴。

供需视角下的长江重庆段江心岛生态管理策略研究

长江重庆段江心岛是流域生态系统中的高生态区位节点,而当前静态保护模式忽略了多元主体对于岛屿生态、社会经济和文化等共融发展的新需求,造成江心岛人地矛盾突出,因此协同好岛屿生态系统服务的供需关系,对促进长江重庆段江心岛生态系统可持续发展和流域国土空间生态文明建设尤为重要。结合长江重庆段14个江心岛生态系统服务供需情况的田野调查,对其生态系统服务供需交互关系进行解读,搭建江心岛生态系统服务供需的空间耦合关联框架,指明统筹好自然空间和多元利益主体的综合治理是促进江心岛“社会—生态”协同发展的关键。在此基础上,从支持与调节服务退化、供给和文化服务价值发挥不足、供需协调综合效能提升不足等三个层面识别出当前造成江心岛生态服务供需矛盾的主要原因,最后整理归纳出岛屿生态管控、系统要素配置和多元主体共治三大策略,以期为更多同类型江心岛的生态管理提供系统性的理论和实践借鉴。

圆截面组合桩加固滑坡的作用机理与合理嵌固深度物理模型试验研究

目前在滑坡治理中,大截面人工挖孔桩因存在施工安全隐患大和效率低下等问题已在部分行业领域被限制使用,开展可机械化施工的圆截面组合桩研究已成为新的趋势,但当前对圆截面组合桩变形受力机理与合理嵌固深度的研究尚不够深入。基于自主研发的圆截面组合桩加固滑坡物理模型试验系统,开展了不同工况下圆截面组合桩加固滑坡的物理模型试验,分析了滑体的变形演化过程,研究了圆截面组合桩加固下滑体与抗滑桩的变形受力特征,并对比分析了不同嵌固深度和桩顶连系梁对圆截面组合桩变形特征的影响,揭示了圆截面组合桩加固滑坡的作用机理。结果表明:①滑体的变形演化过程可分为压密、匀速变形、加速变形和变形破坏4个阶段;②前后桩均存在反弯点,反弯点会随着试验进程向桩顶移动,且后桩的反弯点更接近于滑动面;③当一排桩的嵌固深度保持不变、另一排桩的嵌固深度改变时,可将36%的桩长作为合理的嵌固深度;④连系梁使后桩的最大桩顶位移减小了15.6%,而对前桩的影响不大;⑤连系梁的存在降低了滑动面处的最大桩身弯矩,从而使得桩身弯矩分布更加合理。该研究成果有望为圆截面组合桩的设计提供借鉴和参考。

U形截面包容环优化设计方法研究

U形结构包容环是涡轮起动机通常采用的保护装置。在满足涡轮转子被包容的条件下,对U形截面包容环进行结构优化以获得一个轻便且包容的结构,有利于提高飞机的安全性和推重比。提出了一种U形截面包容环的优化设计方法,该方法采用最优拉丁超立方设计、数值模拟、响应面建模、多岛遗传算法实现包容环截面多参数的优化设计。并通过仿真和试验相结合的方法,分析了不同结构参数对碎片剩余动能和包容环体积的影响权重,研究了U形包容环的不同结构参数对包容结果的影响,并对优化设计后的包容环进行包容性试验验证。结果表明,包容环厚度参数对碎片剩余动能的影响最大,权重比为38%;且影响包容效果主要结构参数是厚度和槽深。仿真与试验结果对比中包容环变形量的误差小于2%,提出的优化设计方法合理可靠。可为U形包容环结构的质量减轻提供先验知识和优化方法。

面向高密度印刷电路板圆形特征的快速铺铜算法

随着印刷电路板的高度集成化,传统的芯片安装和散热无法满足整体尺寸和重量的要求。铺铜作为PCB设计环节中最后进行的关键步骤,在提高电路板性能和有效性方面具有重要作用。本文针对高密度印刷电路板上存在的圆形特征,提出了一种基于完整图形的信息分类和区域计算的快速铺铜算法,并对铺铜过程中产生的孤岛提出了搜索方案。其核心思想如下:首先根据图形信息对大量特征进行区域划分,然后根据碰撞关系对其分簇,基于分簇结果得到外包络边链和孤岛边链,最后通过环和孔的边链关系得到铺铜结果。算法在3.20 GHz、16 GB内存的Windows 10环境下运行,使用工业用例测试数据进行验证。实验结果表明,与开源的基于拟合多边形的铺铜工具相比,在面向大规模场景时,铺铜结果不依赖于拟合多边形边数,时间缩短了约60%。

孤岛工作面覆岩结构演化及区段煤柱稳定性

为探究浅埋煤层孤岛工作面开采时覆岩结构演化及区段煤柱稳定性,以泰华煤矿50104工作面为工程背景,采用理论分析、数值模拟、现场实测相结合的研究手段,分析其两侧区段煤柱承载能力及区段煤柱覆岩结构演化特征;并利用FLAC 3D数值软件,模拟塑性区分布情况以及采动应力演化特征。结果表明:50104工作面推进过程中,东西两侧区段煤柱塑性破坏滞后于工作面推进过程,位于工作面后方采空区处的区段煤柱处于塑性破坏状态,而位于工作面煤壁前方的煤柱存在稳定的弹性区,整体保持稳定,且两侧区段煤柱应力分布呈现相同特征,2条11 m煤柱高应力集中区域保持对称,均位于工作面后方;工作面区段煤柱高应力破坏区域发展速度滞后于工作面推进速度,工作面前方区段煤柱中心区域平均应力值从3.35 MPa增加至3.54 MPa,但始终未超过理论计算得到的煤柱承载强度值;通过分析50104工作面的矿压监测数据,得出实测初撑力均值为3932.4 kN,占液压支架额定初撑力的55%;平均最大工作阻力5812.3kN,占额定工作阻力的61.2%;加权平均阻力均值为4836.6kN/架,占额定工作阻力的50.9%;最大来压6013 kN,支架应力约2.35 MPa,证明11 m煤柱稳定,位于工作面煤壁前方区段煤柱的整体稳定性较好。

支管轴压下高强钢圆管X形节点的承载力计算公式

研究了支管受压的Q460、Q690、Q960高强钢圆管X形节点的静力性能。采用经试验数据验证的有限元模型进行节点有限元参数分析,研究高强钢牌号、支管与主管外径之比(β)、主管外径与其管壁厚度之比(2γ)、主管轴向应力比(n)对节点性能的影响;与有限元参数分析和文献中试验结果对比,评价我国钢结构设计标准计算公式的适用性。结果表明,节点发生主管塑性破坏,节点承载力多由主管局部变形限值(3%主管外径)确定;多数情况下钢结构设计标准计算公式高估了高强钢圆管X形节点的承载力;主管受到压力或较大拉力时均会降低节点承载力。最后,针对不同钢材牌号的圆管X形节点给出了建议的2γ范围。基于主管塑性破坏,提出了考虑高强钢屈服强度、主管拉压效应的圆管X形节点承载力计算公式。

孤岛工作面沿空掘巷合理煤柱宽度数值模拟研究

随着煤矿开采深度的不断增加,井下生产环境逐渐变得恶劣。为了保障生产的正常接续,煤矿经常采用跳采的方式,造成了孤岛工作面的存在。基于已有的研究发现,留设合理宽度的护巷煤柱是维持巷道稳定性的主要方法之一。为了获取柴里煤矿263_下17工作面区段煤柱的合理宽度,采用数值模拟方法,研究了不同时期、不同煤柱宽度条件下,区段煤柱内应力分布情况和围岩表面位移变化情况,确定了263_下17工作面合理的区段煤柱宽度为6 m。经过现场实践验证,263_下17工作面巷道围岩控制方案合理有效,相关经验可以为相似工作面巷道维护提供借鉴。