Comparing the bullwhip effect under different inventory policies in engineering project supply chains

Measuring bullwhip effect is useful for making better controls on production planning and enhancing the supply chain operating efficiency.First,this article establishes the comparative analysis model of bullwhip effect between(s,S)and Periodic Review(PR)inventory policy based on the quantitative bullwhip effect model under different inventories.Then,the impacts of lead time,inventory review time,autocorrelation coefficient,and the number of samples on the gap of bullwhip effect under(s,S)and PR IP are analyzed.The results show that bullwhip effect in PR is more intense than(s,S)inventory policy.Contractors should pay more attention to control bullwhip effect when adopting PR inventory policy to enhance the total operating efficiency of the engineering project supply chains.

Effect of salt solutions on chain structure of partially hydrolyzed polyacrylamide

The effect of salt solutions(NaCl,Na2SO4 and CaCl2) on the conformational properties of partially hydrolyzed polyacrylamide(HPAM) was investigated by using static laser light scattering(SLLS).The special interaction between CaCl2 solution and HPAM was also researched.Experimental results show that the chain structure of HPAM is interrelated with the charge density,the kind and the concentration of salt solutions.The mean-square radius of gyration(Rz) and the second virial coefficient(A2) of HPAM decrease with increasing concentration of salt solutions,and the salt effect tends towards the maximum when the concentration of salt solution is increased to some amount.

STUDIES ON THE CHAIN STRUCTURAL EFFECT OF PVDF AND VDF (52)/TrFE(48) COPOLYMER BY MEANS OF THE METHOD OF DIELECTRIC RELAXATION

Through improvements on a fully commercial and automatic system measuring frequency andtemperature spectra of the complex elastic, dielectric, and piezoelectric constants of polymerfilms, the precision for measuring complex dielectric constants achieved 2‰ from original 1%.The complex dielectric constants of PVDF, VDF （95 ）/VF （5）, VDF （52）/TrFE （48） and VDF（47. 5）/TrFE（47. 5）/HeFP （5） over a range of-120-140℃, 10-2-10;Hz were measured bythe described system. The diminution of chain regularity due to 5mol% vinyl fluoride in the chainof PVDF led to disappearing of α-relaxation and increase in T;（3℃） of VDF （95）/VF （5）.Because of the spatial impediment of 5mol% HeFP in copolymer chain, the Curie point of VDF（52）/TrFE（48） decreased by 30℃ and T;by 3℃. The behavior of dielectric relaxation indicatedthat 5mol% vinyl fluoride and HeFP made the relaxation strength of noncrystalline regionreduced, the activation energy of local relaxation increased and the relaxation time prolonged respectively.

Effective-field and Monte Carlo studies of mixed spin-2 and spin-1/2 Ising diamond chain

The magnetic properties of a mixed spin-2 and spin-1/2 ferromagnetic diamond chain are studied by effective-field theory and Monte Carlo（MC） simulation based on the Ising model.The temperature dependences of magnetization,magnetic susceptibility,internal energy,and specific heat are studied,respectively.The exchange interaction dependences of magnetization and the critical temperature are calculated by MC simulation.The changes of magnetization depending on the field increasing and then the field decreasing under steady-static conditions are also given.

Mechanism for Increasing Effective Inputs in Urban Agriculture through Industrial Value Chain

This paper firstly introduces the value chain management thought,current situations of utilization,and connotation of mechanism for increasing effective inputs in urban agriculture through industrial value chain.On the basis of basic idea of value chain management,this paper is to explore the mechanism for increasing effective inputs in urban agriculture through the value chain of urban agriculture linking with other industries.

Size Effect on the Raman Spectra and Electronic Structure of the Glycine-alanine Oligopeptide Chains

A theoretical study on oligopeptide chains of glycine-alanine by density functional theory（DFT） is given in this paper. Raman spectra of the oligopeptide chains are examined. The geometric structures, frontier orbital, energy gap, atomic charge distribution, density of states and chemical activity of the side chain are studied at the B3LYP/6-31G（d） level. Results show that, with the number of residues increasing, vibrations of typical functional groups present Raman frequency shift, and the energy gap is gradually reduced. The HOMO and LUMO focus on the amino and carboxyl at the ends of oligopeptides. It is helpful for oligopeptides to self-assemble into chains. In addition, different residues（glycine or alanine） at the ends of chains result in the even-odd effect of orbital energy in the growth process. The size effects of physical and chemical properties only exist when the oligopeptides are shorter, and the phenomenon disappeared as the chain continues to grow.

Applying IT to Avoid Bullwhip Effect of Supply Chain

Bullwhip effect is the most important factor considered in the supply chain management. It gets many scholars＇ attention that bullwhip effect has been restricting the development of the supply chain all the time. Information Technology （IT） can reduce bullwhip effect by sharing the information among the enterprises in the supply chain.

基于马尔可夫链的COVID-19流行病患病区域变化趋势预测

在COVID-19疫情环境下,为精准预测不同症状状态的人群人数和区域级别的发展趋势,以SIR传染病模型为基础,基于马尔可夫链预测时空相关的特性,设计了感染人群状态与管控措施相关的K-SIRD传染病预测模型.根据COVID-19疫情人群之间传染性的特征及受距离影响造成有效传染数R e的变化而导致不同的症状状态改变的转移规律,实时精准预测了不同状态的人员人数变化,并根据同一区域人群症状状态分布情况不同,针对不同级别的区域采用不同等级的管控措施.

A Study of the Bullwhip Effect for Short Life Cycle Products in Supply Chain Management

Shorter product life cycles present new dressed in supply chain literature. This research challenges to managing production and logistics not adequately adaddresses issues pertaining to the management of supply chains in a short life cycle environment. In this paper, we study the short life cycle environment; then we develop the ventory policy of the indirect manufacturer by explicitly using his demand us an output of the retailer＇s optimal inoptimal ordering policy. Finally, we also provide causes of the bullwhip effect in the context of short life cycle products.

供应链管理中的牛鞭效应(Bullwhip Effect)现象研究——以图书供应链为例

基于国内外对BullwhipEffect现象的研究现状,分析了我国图书供应链中普遍存在BullwhipEffect现象的原因及其危害性。

喉罩在胸腔镜下交感神经链切断术的应用效果

目的:探讨手汗症双侧胸腔镜下交感神经链切除术患者实施喉罩全身麻醉(以下简称全麻)和双腔气管插管全麻的临床效果。方法:回顾性分析2023年10月—2024年5月收治的40例单孔法完成手汗症病例的临床资料,随机分对照组和观察组,每组20例。对照组实行双腔气管插管全麻,观察组实行喉罩全麻。比较两组麻醉复苏时间、双侧手术总时间、术中出血量、术后视觉模拟疼痛评分(VAS)、住院时间和住院费用、术后并发症发生率及应激反应指标。结果:观察组麻醉复苏时间短于对照组(P<0.05);两组双侧手术总时间、术中出血量比较,差异无统计学意义(P>0.05);观察组术后1 d的VAS评分和白细胞计数(WBC)水平低于对照组,住院时间短于对照组,住院费用少于对照组(P<0.05);观察组术后咽痛、呛咳等发生率低于对照组(P<0.05);两组术后1 d的炎症因子水平较之前均呈升高趋势,但观察组白细胞介素-6(IL-6)、肿瘤坏死因子(TNF-α)、C反应蛋白(CRP)水平低于对照组(P<0.05);术后1 d观察组皮质醇(COR)、去甲肾上腺素(NE)水平均低于对照组(P<0.05)。结论:胸腔镜下交感神经链切断术中实施喉罩全麻,有效且安全,与双腔气管插管全麻相比,具有减轻术后疼痛、降低并发症风险、节约住院时间等突出优势。

Controllable wave propagation in a weakly nonlinear monoatomic lattice chain with nonlocal interaction and active control

The one-dimensional monoatomic lattice chain connected by nonlinear springs is investigated, and the asymptotic solution is obtained through the Lindstedt-Poincar′e perturbation method. The dispersion relation is derived with the consideration of both the nonlocal and the active control effects. The numerical results show that the nonlocal effect can effectively enhance the frequency in the middle part of the dispersion curve.When the nonlocal effect is strong enough, zero and negative group velocities will be evoked at different points along the dispersion curve, which will provide different ways of transporting energy including the forward-propagation, localization, and backwardpropagation of wavepackets related to the phase velocity. Both the nonlinear effect and the active control can enhance the frequency, but neither of them is able to produce zero or negative group velocities. Specifically, the active control enhances the frequency of the dispersion curve including the point at which the reduced wave number equals zero, and therefore gives birth to a nonzero cutoff frequency and a band gap in the low frequency range. With a combinational adjustment of all these effects, the wave propagation behaviors can be comprehensively controlled, and energy transferring can be readily manipulated in various ways.

Seismic fluid identification using a nonlinear elastic impedance inversion method based on a fast Markov chain Monte Carlo method

Elastic impedance inversion with high efficiency and high stability has become one of the main directions of seismic pre-stack inversion. The nonlinear elastic impedance inversion method based on a fast Markov chain Monte Carlo （MCMC） method is proposed in this paper, combining conventional MCMC method based on global optimization with a preconditioned conjugate gradient （PCG） algorithm based on local optimization, so this method does not depend strongly on the initial model. It converges to the global optimum quickly and efficiently on the condition that effi- ciency and stability of inversion are both taken into consid- eration at the same time. The test data verify the feasibility and robustness of the method, and based on this method, we extract the effective pore-fluid bulk modulus, which is applied to reservoir fluid identification and detection, and consequently, a better result has been achieved.

数字经济发展如何影响城市碳排放?——来自中国283个地级市的经验数据

为探讨数字经济对城市碳排放的影响,基于2011—2020年中国283个地级以上城市的面板数据,构建综合评价指标体系测算数字经济指数,核算各城市碳排放量,采用SBM模型测算城市碳排放效率,并以产业结构高级化和合理化指数来刻画城市的产业结构升级,在此基础上进行计量分析。结果发现:数字经济发展能够提升碳排放效率,二者呈现出“U”型关系,数字经济发展能够降低碳排放强度和减少碳排放量,均呈现出倒“U”型关系;数字经济能够通过技术创新或产业结构升级影响碳排放,且技术创新和产业结构升级在数字经济与碳排放之间存在链式中介效应;数字经济、技术创新和产业结构升级对城市碳排放存在门槛效应,数字经济和技术创新在门槛值前后对碳排放效率的影响均呈现“先抑后扬”,对碳排放量的影响为“先扬后抑”,对碳排放强度跨越门槛后有显著的抑制作用,产业结构高级化和合理化指数跨越门槛值后能够提高碳排放效率、减少碳排放量,但对碳排放强度不产生影响。最后,基于实证结论提出了相应的政策建议。

临床护士感知社会支持和抗逆力在职业倦怠与抑郁间的链式中介效应

目的探讨感知社会支持和抗逆力在临床护士职业倦怠对抑郁影响机制的多重中介作用,为开展干预以促进护士心理健康提供参考。方法基于资源保护理论,采用职业倦怠量表、感知社会支持量表、抗逆力量表和抑郁量表对1574名临床护士进行调查,构建并检验链式中介模型。结果护士职业倦怠得分为2.19(1.33,3.02)分,感知社会支持得分为71.00(59.00,80.00)分,抗逆力得分为30.00(22.00,34.00)分,抑郁得分为8.00(2.00,10.00)分;职业倦怠与感知社会支持及抗逆力呈负相关,与抑郁呈正相关,感知社会支持和抗逆力与抑郁呈负相关(均P<0.05)。职业倦怠对抑郁影响的总效应为0.441,感知社会支持和抗逆力在职业倦怠对抑郁的影响中起部分中介作用,中介效应分别占11.56%和14.74%,两者的链式中介效应占总效应的14.51%。结论临床护士职业倦怠和抑郁负性心理问题仍较为严重。感知社会支持和抗逆力在护士职业倦怠与抑郁间起链式中介作用。可通过提高护士群体的感知社会支持和抗逆力水平,以帮助其缓解职业倦怠对抑郁的影响,改善其心理健康。

“资本+技术”融合驱动下产业转移升级与经济高质量发展

技术创新作为经济高质量发展的持久动力,离不开充足的资本支持。本文基于我国30个省区市(未包括港澳台和西藏)面板数据,研究资本与技术融合驱动、产业转移升级和经济高质量发展的关系。研究结果显示:在产业转承两地,资本与技术融合驱动水平在促进经济高质量发展的同时,能够正向调节产业结构升级对经济高质量发展的促进作用;然而,在资本与技术融合驱动下,产业转移对产业结构升级和经济高质量发展的影响具有显著的地区异质性和行业异质性;机制分析显示,产业承接地的资本与技术融合驱动主要通过推动产业结构升级的独立中介效应渠道和“抑制产业转移承接→促进产业结构升级”的链式中介渠道推进经济高质量发展,产业转出地的资本与技术融合驱动主要是通过促进产业结构升级的中介效应渠道推进经济高质量发展。本文提出促进资本与技术的融合发展,立足区域差距制定差异化的发展战略,重视传统行业与高新技术行业的深度融合,着力推动承接地产业结构迈向中高端等建议,以此驱动经济高质量发展。

数字经济如何影响制造业产业链韧性?

数字经济是理解制造业产业链韧性的重要视角。本文利用2011-2021年全国各省面板数据,实证探究数字经济提升制造业产业链韧性的内在机理,识别数字经济提升制造业产业链韧性的作用路径。研究结果表明:(1)数字经济通过提高创新资源的配置水平提高制造业产业链韧性;(2)随着数字产业化和产业数字化,数字经济对制造业产业链韧性促进作用边际递减;(3)数字资源是数字经济发展初期促进制造业产业链韧性提升的主要因素,数字经济促进作用下降的原因是数字应用推动作用的下降;(4)数字经济对中部地区制造业产业韧性促进作用最大。本文试图分解数字经济要素,并具体分析各要素对制造业产业链韧性的影响。

留守儿童领悟社会支持对学业情绪的影响——基于链式中介效应检验

为探讨留守儿童领悟社会支持对学业情绪的影响,并检验自尊和希望在此影响过程中的中介效应,课题组运用问卷调查法对1210名被试进行调查.结果表明,留守儿童的领悟社会支持正向预测积极学业情绪,负向预测消极学业情绪;自尊、希望在留守儿童领悟社会支持与学业情绪间起着链式中介作用.因此,家庭、学校、社区应当三方协同,提升留守儿童的社会支持水平,促使他们融入社会;积极引导,提高留守儿童的自尊水平;主动干预,促进留守儿童希望感的发展;采取多方面的措施,改善留守儿童的学业情绪.

“一带一路”倡议与全球价值链升级——基于沿线国家的实证数据

基于2007—2020年“一带一路”沿线国家的样本数据,利用多期双重差分模型实证检验了“一带一路”倡议对沿线国家的价值链升级作用。研究结果证实:“一带一路”倡议对于沿线国家全球价值链发展具有显著正向影响。机制分析表明:“一带一路”倡议对沿线国家存在“虹吸效应”,有利于沿线国家的发展。此外,政策沟通对于倡议的推行具有积极的促进作用。研究结果不仅证实了倡议对于沿线国家价值链升级的正向影响,也论证了其中存在的影响机制,为未来进一步的研究提供了理论支撑和有益探索。

新质生产力与制造业产业链供应链韧性:理论分析与实证检验

新质生产力能够实现技术革命性突破、生产要素创新性配置、产业深度转型升级,为提升制造业产业链供应链韧性注入新动能.在构建城市层面新质生产力综合测度体系与制造业产业链供应链韧性指标基础上,使用2003-2020年154个地级市的平衡面板数据,实证分析新质生产力对制造业产业链供应链韧性的直接效应与空间溢出效应.研究发现:基准回归结果与异质性检验结果表明,新质生产力能够显著增强制造业产业链供应链韧性,这一结论在不同区域、不同产业结构合理化程度的地区中存在差异;空间计量回归结果表明,新质生产力不仅能够直接增强本地区制造业产业链供应链韧性,且会通过空间溢出效应对邻近地区制造业产业链供应链韧性产生正向影响;进一步分析结果表明,国内价值链的战略替代性能够正向调节新质生产力的制造业产业链供应链韧性提升效应.为制造业产业链供应链突破传统发展模式,提高自主可控能力提供有益参考.