Homotopy analysis solutions for the asymmetric laminar flow in a porous channel with expanding or contracting walls

In this paper, the asymmetric laminar flow in a porous channel with expanding or contracting walls is investigated. The governing equations are reduced to ordinary ones by using suitable similar transformations. Homotopy analysis method （HAM） is employed to obtain the expres- sions for velocity fields. Graphs are sketched for values of parameters and associated dynamic characteristics, especially the expansion ratio, are analyzed in detail.

Analytic solution to the micropolar-fluid flow through a semi-porous channel with an expanding or contracting wall

The flow of a micropolar fluid in a semi-porous channel with an expanding or contracting wall is investigated. The governing equations are reduced to ordinary ones by using similar transformations. To get the analytic solution to the problem, the homotopy analysis method （HAM） is employed to obtain the expressions for velocity fields. Graphs are sketched and discussed for various parameters, especially the effect of the expansion ratio on velocity and micro-rotation fields.

Perturbation solution to unsteady flow in a porous channel with expanding or contracting walls in the presence of a transverse magnetic field

An incompressible flow in a porous channel with expanding or contacting walls in the presence of a transverse magnetic field is considered. Using similarity transformations, the governing equations are reduced to the nonlinear ordinary differential equations. The exact similar solutions for the different cases of the expansion ratio and the Hartmann number are obtained with a singular perturbation method, and the associated behavior is discussed in detail.

政府补贴下考虑风险厌恶的双渠道绿色供应链运营决策及协调契约

在政府对绿色产品提供补贴的基础上,构建以制造商为主导的供应链博弈模型,利用均值方差法分析了在双方风险中性(RN)、双方风险厌恶(RA)、仅制造商风险厌恶(MRA)和仅零售商风险厌恶(RRA)4种模式下的双渠道绿色供应链决策及效用,并设计带有转移支付的成本分担契约以实现协调。研究发现:在RRA模式下,产品绿色度与风险厌恶程度正相关;而在MRA模式和RA模式下,产品绿色度与风险厌恶程度负相关;双方效用在4种模式下均与政府补贴正相关,且在RRA模式下制造商效用受政府补贴的影响最为显著;当研发成本系数较大时,在MRA模式和RRA模式下,一方的效用与另一方的风险厌恶程度正相关,而在RA模式下双方效用与风险厌恶程度负相关。此外,通过数值分析揭示了成本分担比例与风险厌恶程度负相关、与政府补贴正相关。以上结论可为双渠道绿色供应链的决策制定及协调管理提供参考。

不同销售模式下质量投资和自有品牌侵入的交互影响

平台作为线上资源配置媒介,正改变着供应链产业结构和市场消费模式。基于不同销售契约,研究供应链质量投资和平台自有品牌侵入的交互作用。考虑消费者策略偏好,建立8种不同情形下的供应链决策模型;进一步,通过数值分析探讨了供应链销售模式选择、质量投资和渠道结构配置策略。研究表明:供应商和平台对供应链销售模式偏好具有差异性,但通过外生参数控制可以实现局部供应链帕累托改进。供应商质量投资总是可以为其带来额外的收益,但平台自有品牌侵入会提高质量投资门槛。反常识的,当消费者接受度较高时,平台不倾向引入自有品牌,只有当接受度较低时才会选择混合渠道策略。因此,供应链实行差异化产品策略能够缓解竞争、促进消费,更有利于运营。

基于钙通道及心肌收缩机制探讨强心药的应用

心力衰竭是各种心血管疾病的末期阶段,临床表现复杂,难以根治。心肌收缩功能下降是心力衰竭发生的重要原因之一。钙通道在心肌收缩舒张过程中具有关键调控作用,心肌收缩蛋白、心肌能量代谢、心肌兴奋收缩耦联在心脏疾患后期受到各种理化因素影响而出现异常,引起心肌收缩力减弱。心肌收缩功能正常对于维持人体正常生命活动具有决定性意义,临床常根据具体状况分类应用强心药以改善心肌收缩力,效果显著。随着医学技术的进步,强心药种类增多且优势更加突出,未来仍需进一步探讨。

考虑企业社会责任的供应链决策与协调

考虑碳限额交易下由制造商和具有企业社会责任(CSR)的零售商组成的双渠道供应链,通过消费者效用函数构建Stackelberg博弈模型研究不同情况各主体最优均衡决策,利用MATLAB分析CSR、消费者低碳意识以及转移支付费用对均衡结果的影响。研究发现:CSR对集中决策下整体效益有利但会降低减排率,而对分散决策的影响相反;低碳意识越强对减排量、效益、消费者剩余越有利;一定条件下二部定价契约能有效缓解双重边际效应,实现整个供应链系统效益的Pareto改进。

新零售环境下基于渠道迁徙行为的农产品供应链决策优化

有别于大众化消费普遍从线下转移到线上的迁徙路径,个体异质且存在时鲜易腐的农产品消费不仅存在线下至线上的迁徙,同时不乏线上至线下的转移,农产品消费的渠道迁徙路径更加的灵活多元。基于此,分别构建传统环境、新零售环境基于渠道迁徙行为和新零售环境基于成本共担契约的农产品供应链决策模型,计算三种情形下零售商的最优订购量及最优利润水平,并进行了模型对比分析。研究表明,适当的成本共担契约能够在存在消费者渠道迁徙行为时激励提升农产品供应链的服务水平,促进提高农产品订购量并增加供应链主体的收益。

Mechanisms mediating CCK-8S-induced contraction of proximal colon in guinea pigs

AIM:To investigate the effects of sulfated cholecystokinin octapeptide (CCK-8S) on the contractile activity of guinea-pig proximal colon.METHODS:Proximal colonic smooth muscle (PCSM) strips were obtained from adult female guinea pigs and contractile response of PCSM strips was recorded using a polyphysiograph.PCSM cells were isolated by enzymatic digestion.Resting potential (RP),action potential (AP),large conductance potassium channel currents (IBKCa) and L-type calcium currents (ICa-L) were recorded by patch-clamp techniques.RESULTS:(1) CCK-8S (10-7 mol/L) enhanced the mean contractile amplitude of colonic circular muscle and longitudinal muscle (LM) strips by 56.53% ± 11.92%(P=0.038) and 65.93% ± 12.98% (P=0.019),respectively,as well as the mean frequency of LM by 31.69% ± 13.58% (P=0.023),which were significantly attenuated by pretreating strips with devazepide,nifedipine,iberiotoxin,thapsigargin (TG) and BAPTA-AM (BA) respectively;(2) CCK-8S (10-7 mol/L) increased the AP amplitude by 38.6% ± 3.2% (P=0.015),decreased AP duration by 36.9% ± 8.7% (P=0.026),and depolarized the RP from-61.3 ± 2.7 mV to-29.8 ± 5.9 mV (P=0.032);and (3) Compared with the normal control group,CCK-8S (10-7 mol/L) enhanced the peak current of IBKCa by 18.7% ± 2.1% (from 916 ± 183 pA to 1088 ± 226 pA;at +60 mV;P=0.029),which was inhibited by respective pretreatment with iberiotoxin and devazepide.Additionally,CCK-8S (10-7 mol/L) intensif ied the peak current of ICa-L by 40% (from 60 ± 8 pA to 84 ± 11 pA;at +10 mV;P=0.012),compared to the normal control group,which was apparently suppressed by respective pretreatment with nifedipine,devazepide,TG and BA.In the respective presence of heparin and staurosporine,CCK-8S did not signif icantly enhance IBKCa and ICa-L.CONCLUSION:The results suggest that CCK-8S promotes guinea-pig proximal colon contraction by CCK1 receptors,following activation of the inositol triphosphate-protein kinase C signal transduction pathway.

Effects of anti-hypertensive drugs on esophageal body contraction

AIM:To clarify the effects of anti-hypertensive drugs on esophageal contraction and determine their possi-ble relationship with gastro-esophageal reflux disease.METHODS:Thirteen healthy male volunteers were enrolled. Esophageal body peristaltic contractions and lower esophageal sphincter (LES) pressure were measured using high resolution manometry. All subjects were randomly examined on four separate occasions following administrations of nifedipine,losartan,and atenolol,as well as without any drug administration.RESULTS:Peristaltic contractions by the esophageal body were separated into three segments by two troughs. The peak peristaltic pressures in the mid and lower segments of the esophageal body under atenolol administration were signifi cantly higher than those without medication in a supine position. On the other hand,peristaltic pressures under nifedipine administration were lower than those observed without drug ad-ministration. Losartan did not change esophageal body peristalsis. Atenolol elevated LES pressure and slowed peristaltic wave transition,while the effects of nifedip-ine were the opposite. CONCLUSION:Among the anti-hypertensive drugs tested,atenolol enhanced esophageal motor activity,which was in contrast to nifedipine.

Effect of the ginsenoside Rb1 on the spontaneous contraction of intestinal smooth muscle in mice

AIM: To investigate the effect and the possible mechanism of ginsenoside Rb1 on small intestinal smooth muscle motility in mice. METHODS: Intestinal smooth muscle strips were isolated from male ICR mice (5 wk old), and the effect of ginsenoside Rb1 on spontaneous contraction was recorded with an electrophysiolograph. The effect of ginsenoside Rb1 on ion channel currents, including the voltage-gated K + channel current (IK V ), calcium-activated potassium channel currents (IK Ca ), spontaneous transient outward currents and ATP-sensitive potassium channel current (IK ATP ), was recorded on freshly isolated single cells using the whole-cell patch clamp technique. RESULTS: Ginsenoside Rb1 dose-dependently inhibited the spontaneous contraction of intestinal smooth muscle by 21.15% ± 3.31%, 42.03% ± 8.23% and 67.23% ± 5.63% at concentrations of 25 μmol/L, 50 μmol/L and 100 μmol/L, respectively (n=5,P<0.05). The inhibitory effect of ginsenoside Rb1 on spontaneous contraction was significantly but incompletely blocked by 10 mmol/L tetraethylammonium or 0.5 mmol/L 4-aminopyridine, respectively (n=5, P<0.05). However, the inhibitory effect of ginsenoside Rb1 on spontaneous contraction was not affected by 10 μmol/L glibenclamide or 0.4 μmol/L tetrodotoxin. At the cell level, ginsenoside Rb1 increased outward potassium currents, and IK V was enhanced from 1137.71 ± 171.62 pA to 1449.73 ± 162.39 pA by 50 μmol/L Rb1 at +60 mV (n=6, P<0.05). Ginsenoside Rb1 increased IK Ca and enhanced the amplitudes of spontaneous transient outward currents from 582.77 ± 179.09 mV to 788.12 ± 278.34 mV (n=5, P<0.05). However, ginsenoside Rb1 (50 μmol/L) had no significant effect on IK ATP (n=3, P<0.05). CONCLUSION: These results suggest that ginsenoside Rb1 has an inhibitory effect on the spontaneous contraction of mouse intestinal smooth muscle mediated by the activation of IK V and IK Ca , but the K ATP channel was not involved in this effect.

Effect of gingerol on colonic motility via inhibition of calcium channel currents in rats

AIM: To investigate the effect of gingerol on colonic motility and the action of L-type calcium channel currents in this process.METHODS: The distal colon was cut along the mesenteric border and cleaned with Ca^(2+)-free physiological saline solution. Muscle strips were removed and placed in Ca^(2+)-free physiological saline solution, which was oxygenated continuously. Longitudinal smooth muscle samples were prepared by cutting along the muscle strips and were then placed in a chamber. Mechanical contractile activities of isolated colonic segments in rats were recorded by a 4-channel physiograph. Colon smooth muscle cells were dissociated by enzymatic digestion. L-type calcium currents were recorded using the conventional whole-cell patch-clamp technique.RESULTS: Gingerol inhibited the spontaneous contraction of colonic longitudinal smooth muscle in a dose-dependent manner with inhibition percentages of 13.3% ± 4.1%, 43.4% ± 3.9%, 78.2% ± 3.6% and 80.5% ± 4.5% at 25 μmol/L, 50 μmol/L, 75 μmol/L and 100 μmol/L, respectively(P < 0.01). Nifedipine, an L-type calcium channel blocker, diminished the inhibition of colonic motility by gingerol. Gingerol inhibited L-type calcium channel currents in colonic longitudinal myocytes of rats. At a 75 μmol/L concentration of gingerol, the percentage of gingerolinduced inhibition was diminished by nifedipine from 77.1% ± 4.2% to 42.6% ± 3.6%(P < 0.01). Gingerol suppressed IBa in a dose-dependent manner, and the inhibition rates were 22.7% ± 2.38%, 35.77% ± 3.14%, 49.78% ± 3.48% and 53.78% ± 4.16% of control at 0 m V, respectively, at concentrations of 25 μmol/L, 50 μmol/L, 75 μmol/L and 100 μmol/L(P < 0.01). The steady-state activation curve was shifted to the right by treatment with gingerol. The value of half activation was-14.23 ± 1.12 m V in the control group and-10.56 ± 1.04 m V in the 75 μmol/L group(P < 0.05) with slope factors, Ks, of 7.16 ± 0.84 and 7.02 ± 0.93(P < 0.05) in the control and 75 μmol/L groups, respectively. However, the steady-state inactivation curve was not changed, with a half-inactivation voltage, 0.5 V, of-27.43 ± 1.26 m V in the control group and-26.56 ± 1.53 m V in the 75 μmol/L gingerol group(P > 0.05), and a slope factor, K, of 13.24 ± 1.62 in the control group and 13.45 ± 1.68(P > 0.05) in the 75 μmol/L gingerol group.CONCLUSION: Gingerol inhibits colonic motility by preventing Ca^(2+) influx through L-type calcium channels.

Numerical Studies of Turbulent Flows in Channels with Abrupt Cross-sectional Changes

The turbulent flows through the channels with abrupt cross-sectional changes are common and importantphysical process in nature.For a better prediction of the mean flow and turbulent characteristics for this problem,atwo-dimensional depth-averaged numerical model is developed.The model is robust and accurate in reproducing therecirculation flow behind a groyne and turbulent flows in channels with abrupt cross-sectional changes,when com-pared to the available experimental data of mean velocities and turbulence kinetic energy.Our results reveal that theabrupt cross-sectional change of a channel can affect the flow pattern significantly and introduces the complex turbu-lence characteristics.In particular,when the channel has an abrupt expansion,the mean flow pattern is mainly in lon-gitudinal direction with rather small transverse component.Meanwhile,a recirculating region forms behind the expan-sion position and the turbulence has very strong intensity within this region.For the flow in the channel with an ab-rupt contraction,the longitudinal component of the flow is decreased by the obstruction on one side and accelerated onthe other side,whereas the transverse velocity is small.The turbulence is extraordinarily strong in the regions adja-cent to the contraction wall in the narrow channel.In both cases of abrupt cross-sectional changes,the TKE is genera-ted dominantly by the shear of the longitudinal velocities.

低频脉冲磁场慢性暴露对健康成年股四头肌收缩力及形态的影响

背景:目前已有关于低频脉冲磁场对骨骼肌结构形态影响研究发现了骨骼肌质量变化,但对接受慢性暴露后的形态变化未见相关研究。目的:观察低频脉冲磁场慢性暴露对腿部股四头肌最大自主收缩力与形态指标的影响,为使用该技术作为肌肉功能改善策略提供组织形态变化的参考依据。方法:招募普通健康受试者70名,随机分为接受磁场刺激的试验组与进行假治疗的对照组,每组35名,试验时长共计4周,试验组受试者每隔48 h进行1次15 min的低频脉冲磁刺激干预,对照组进行假治疗,干预间隔与时长与试验组一致,干预4周后观察不同组别受试者股四头肌最大自主收缩力值变化,利用B型超声影像作为评估手段,观察肌肉厚度、肌肉横截面积及羽状角指标的变化。结果与结论:①经过4周的低频脉冲磁场慢性暴露,68名受试者完成试验,试验组受试者股四头肌最大自主收缩力测试值显著增长(P=0.000),提升幅度显著高于对照组(P=0.008);②试验组受试者的肌肉形态3项指标均显著高于试验前测(P=0.000),而对照组肌肉厚度指标呈显著性下降(P=0.020),羽状角无显著性变化,横截面积显著性提升(P=0.000);③组间对比发现,试验组关于肌肉形态的肌肉厚度(P=0.012)、羽状角(P=0.003)及横截面积(P=0.049)3项指标均显著高于对照组;④上述数据证实,健康成年受试者经过4周的低频脉冲磁场慢性暴露,股四头肌的最大自主收缩力显著提升,同时观察到试验组的肌肉厚度、横截面积及羽状角3项肌肉形态指标的显著增长,对使用该技术作为肌肉改善的运动替代与医疗策略提供了肌组织形态改善的支持依据。

基于营业中断保险的双渠道供应链应急运作决策研究

疫情、地震等突发事件频发,营业中断保险经常被作为转移风险的应急管理措施。以营业中断保险为主线,构建供应商优先购买保险和零售商跟随定价的双渠道供应链投保与定价优化决策模型,设计有效的收益共享契约进行协调,并拓展到供应商与零售商在线上直销与线下零售差异定价的情况。研究结果表明,参与营业中断保险,保险赔偿抵消了惩罚成本与缺货成本对价格的提高作用,供应商与零售商都倾向于降价促销以提高自身利润。供应商投保时,线上直销需求占比越大,保费率越小,供应商投保意愿越强烈;线下零售需求占比越大,购买保险对供应商的风险转移效果越弱,对零售商风险转移效果越强。交叉价格弹性较大时,零售商更偏好于差异定价。

激光真空传输通道及光学舱应力补偿技术

介绍了真空通道应力补偿结构的基本工作原理;研究了大温差环境下,激光束长距离真空传输通道的真空负压应力和热胀冷缩应力的自适应补偿技术和光学舱结构变形抑制技术;在整个光学系统上,开展了现场安装调试和真空负压应力考核,并进行环境温差变化情况下的光路传输稳定性试验验证。试验结果表明:解决了超长激光束真空传输通道在真空负压和大温差环境下的真空负压应力和热胀冷缩应力的自适应补偿问题和光学舱结构变形抑制问题;实现了传输通道真空负压应力自动平衡;消除了真空负压应力造成的光束漂移;实现了大温差环境下的真空负压通道结构热胀冷缩应力的自由释放;达到了光路长时间保持稳定的实际效果。

策略性消费者影响下的双渠道供应链合同选择

研究了存在策略性消费者且零售商在原有线下渠道基础上开通线上渠道时,制造商与零售商供应链合同的选择问题。通过逆推法比较不同供应链合同下,制造商与零售商做分散决策和集中决策获得的收益以及零售商线上线下不同渠道定价决策对供应链整体收益的影响,讨论制造商和零售商的最优决策。得出主要结论为:在一般情况下数量折扣合同能更好的协调供应链,增加整体收益;然而当策略性消费者的耐心程度,对线上销售渠道接受程度增加时,批发价格合同更适用于考虑零售商开通线上销售渠道的情况。

考虑随机参照价格的双渠道绿色供应链定价和渠道策略研究

为了探讨参照效应对绿色供应链成员决策的影响,将消费者的随机参照价格引入到双渠道绿色供应链中,通过博弈论方法构建一个两阶段Stackelberg模型,讨论了线上线下的一致性定价策略。结果表明:当消费者的绿色偏好系数较高时,消费者参照价格的离散程度对制造商和零售商有利;否则,消费者参照价格的离散程度对制造商有利但对零售商不利;随着消费者参照价格敏感性系数的增大,制造商的期望利润先减小后增大,但零售商的期望利润单调下降;收益共享和成本分担组合契约能够协调双渠道绿色供应链。通过与单渠道绿色供应链均衡的比较发现,制造商进入线上渠道的条件受到消费者参照价格敏感性系数和离散程度的双重影响。在此基础上将模型拓展到差异化定价,讨论了不同定价策略对渠道成员的影响。

平台销售模式下制造商渠道设计与协调策略

考虑了拥有传统零售渠道的制造商是否应该新增平台销售渠道,并将平台渠道带来的市场拓展、渠道竞争以及佣金费率引入供应链决策模型,通过构建增加平台渠道前后的供应链决策模型,分析制造商的渠道设计策略及其对传统零售商利润的影响。随后,针对新增平台渠道导致的渠道冲突,设计带固定补偿的批发零售价格契约对供应链进行协调。研究表明:新增平台渠道可能会伤害制造商和传统零售商的利润,或者伤害其中一方利润,或者增加双方利润,这取决于平台渠道带来的潜在市场大小;当偏好传统渠道的消费者比例低于(高于)某个阈值时,制造商通过双渠道(传统渠道)进行产品销售;批发零售价格契约可以实现供应链的协调,但仅在特定情形下可以同时改善制造商和传统零售商的利润;在批发零售价格契约的基础上设计固定补偿值,可以实现制造商和传统零售商利润的帕累托改进,固定补偿值的范围受消费者渠道偏好的影响。

基于智能合约和数字签名的马铃薯种薯防窜溯源研究

随着区块链技术在农产品溯源领域研究的不断发展,农产品的质量安全得到有效保障。由于我国马铃薯种薯生产过程复杂、实物形态差异化明显、每个环节的生产周期长、品种繁多等原因,所有生产环节的溯源数据共享难度大,容易发生种薯品种、等级等窜货问题,种薯生产溯源无法得到切实保障,生产基地及相关监管部门无法得到全部有效溯源数据,当发生窜货问题以及最终消费者进行种薯生产溯源时,责任环节定位不明确,难以准确找到责任生产环节及相关责任人等问题源头。基于上述问题,提出了基于智能合约和数字签名的马铃薯种薯防窜溯源模型,利用区块链技术不可篡改、数据透明、数据共享等特点,通过智能合约进行种薯生产全环节溯源数据的上链存储,实现种薯生产全环节溯源数据的高度共享,并将智能合约与数字签名相结合,利用公私钥对验证和智能合约高度自治的区块链网络生态环境,解决生产过程中易发生的生产窜货问题。基于Hyperledger Fabric设计面向种薯生产基地的防窜溯源模型,相关测试结果表明,该模型可以实现种薯生产溯源、防窜、窜货报警信息上链与查询等功能。种薯生产溯源数据的平均上链时间为2566 ms,平均查询时间为95 ms,报警触发与报警信息上链的平均时间为2562 ms,查询具体报警信息的平均时间为77 ms。模型综合性能较高,能够实现种薯生产全环节溯源数据的安全存储,并有效解决种薯的生产窜货问题,满足种薯生产溯源数据的上链与查询需求,完善种薯生产质量溯源保障,为防止种薯生产窜货以提高整体效率和安全溯源方面提供了借鉴和参考。