我国北方半干旱草原沙漠化防治中压力转移模式的检讨——以内蒙古巴林右旗为例

以内蒙巴林右旗为例 ,详细分析了目前我国北方半干旱草原沙漠化防治中所主要采用的几种方法——围封禁牧、生态移民、舍饲和小草库伦。提出这些方法都属“压力转移模式”,并指出了其失效的各种表现。进而通过分析我国北方半干旱草原沙漠化的主要原因和根本矛盾 ,指出其失效的根本原因。据此 ,提出要将“压力转移模式”转向“攻坚模式”

环境压力转移视角下电力行业生态效率区域差异研究

将电力行业排放的CO2、SO2、废水和固体废弃物作为环境压力指标,在对随电力转移同时转移的环境压力进行责任分摊的前提下,利用超效率SBM模型和GML指数法测度我国电力行业的生态效率演变过程,并与传统测度结果进行对比,通过GML指数来分解生态效率变化的内在驱动因素。研究结果表明:环境压力转移视角下我国电力行业的生态效率呈由东南向西北递减的空间分布特征,效率变化逐年不断提升但呈"W"型波动趋势;技术进步是提升电力行业生态效率的关键因素,规模效率会抑制效率的提高,规模效率和纯技术效率的区域差异性比技术进步因素明显。最后,基于研究结论提出相应对策建议。

新时期的“娘家与婆家”:性别比例失衡下的压力转移

李霞博士通过“娘家-婆家”分析框架,阐释了“70后”农村青年女性建构亲属关系的实践应用过程。本研究以华东地区芦山村为田野点,将“90后”农村已婚青年女性作为研究对象,从权力结构的视角出发,以女性亲属关系的实践为理论基石,分析新时期农村女性建构的亲属关系之中的权力结构。结果显示,在性别比失衡的现状下,“娘家-婆家”权力结构是一种转圈式压力转移的结构,看似是女方家长将高额的结婚成本转移到男方家庭,实则每个家庭都在承受着高额结婚成本。本质上,稀缺的女性资源是性别比例失衡的结果,但是她们却又是这一恶果的承担者。

纸浆:高位震荡 压力转移

2021年3月针叶木浆进口市场外盘价格继续走高,但现货市场价格有所下滑,期货盘面价格冲破1000美元/t后回落至900美元/t附近。3月本轮供应商报盘涨幅在80~150美元/t不等,供应商及代理商表示涨幅均已落实,在进口美元成本支撑下针叶木浆很难继续下行。

“狡猾”的法院:司法运作中压力转移现象透视

现实司法实践中,法院面对外部不正当干预,往往采取多种手段进行压力转移。这种行为实际上是中国当下司法场域中各种权力合力作用的结果,它既是法院的一种无奈,也是一种策略,一种嵌在政治和权力复杂网络之中的挣扎,往往是一种官僚之间采用的斗争方式,部分地具有为司法独立而战的因子。尽管其中具有诸多的可被批判成分,但是批评不能解决问题,我们需要的是一种建构。如若可能,我们可以文中的案例为切口,探寻协调司法运作规范性与现实适应性之间两者相互过渡的中介。

论长寿内卷化

进入长寿时代后,农村老年人在其高龄阶段的生命历程中,会遭遇各种负性生活事件。伴随其机体衰退,他们会不可避免地坠入巨大的生活风险之中。结合中国传统的老龄观,通过对“内卷化”这一概念的辨析和创造性转化,可以构建“长寿内卷化”的概念,以理解当前农村高龄老年人的生活风险状态。当高龄老年人的生命历程步入内卷点之后,其寿命虽然仍然在延长,但由于各种负性生命事件的发生和影响,生命质量却开始下滑,与理想状态相反的是,这段生命历程将持续进入病寿、苦寿、辱寿等单一存在或同时并存的生活风险状态;当这一曲线下滑至接近生命质量轴的交叉点时,它意味着高龄老年人生命主动或被动的终结。支撑从长寿内卷化到生活风险发生的机制是,城镇化进程带来的社会压力通过环状结构的新家庭结构形式向高龄老年人转移。秉持积极老龄观,加强政策干预,实现长寿去内卷化,是长寿时代所必需面对的重要议题。作为一个分析性概念的“长寿内卷化”,不仅对理解当前农村高龄老年人的生活风险具有理论意义和政策意义,将来也同样适用于分析城市高龄老年人的生活风险状况。

社会替代性补偿与压力应对:旅游的中介效应验证

后现代意义上的旅游作为对工业文明副产品——工作程式化、生活单调化、环境劣质化、人际疏远化的"逃避",已经超越了对求新求异审美的需求而导向对人的社会化的思考。文章通过构建旅游与压力转移整合模型,对旅游是否包含压力转移功能进行了实证检验。研究结果表明,旅游在压力感知与压力转移之间发挥中介效应,从而证明了旅游包含有社会补偿与整合功能,能够帮助个体在他领域寻求一种替代性办法来重新塑造自我,恢复人格尊严。我们应走出囿于旅游经济属性的窠臼,在构建和谐社会的时代主题下,充分挖掘旅游的社会功能,落实带薪休假制度,改善公民工作生活质量,从而全面促进社会福利的帕累托改进。

浅析大学生如何进行压力管理

大学生是个特殊的群体，是迈向社会的前奏，就业压力、经济压力、学业压力是每个大学生都要面临的，过大的压力不仅影响学生的学业成绩，而且影响他们的身体和心理健康。因此对于大学生来说，如何对自身的压力进行适当的管理正确的面对各种压力就非常重要。

大直径钻孔卸压技术在深部冲击地压防治的应用

随着徐矿集团本部各矿进入深部开采，冲击地压成为主要的安全隐患之一。大直径钻孔卸压技术是一种实施简单、效果较好的冲击地压防治方法。通过在庞庄煤矿95209工作面采用大直径钻孔卸压的实例及其取得的效果，说明大直径钻孔卸压技术在深部冲击地压防治的可行性。

近距离煤层群切顶留巷覆岩应力及变形响应研究

为了深入了解近距离煤层群切顶留巷上覆岩层应力及变形演化规律,以白皎煤矿B_(4)煤层、B_(3)煤层、B_(2)煤层切顶成巷巷道2442、2443及2444运输平巷为研究对象,开展了3层煤回采巷道开挖物理试验研究,结果表明:(1)上煤层巷道切顶后,顶板卸压;煤层开挖后,采空区顶板垮落并支撑巷道顶板,顶板增压;煤层继续开挖,覆岩断裂,顶板卸压;巷道顶板应力依次经历卸压、增压及卸压过程,其中,高位顶板应力增加较大,应力较高。(2)中部巷道切顶及煤层开挖后,上覆岩层压力同时向上煤层巷道围岩及本巷道采动破碎压实围岩转移,并在两巷道之间的上覆岩层中形成应力增高区。(3)下煤层巷道切顶及煤层开挖后,巷道围岩破坏严重,无集中应力,受前两次开挖卸压影响较大。(4)上覆岩层沿层理面出现错动变形,同时出现垂直拉伸剪切裂纹,采动影响越大,裂纹扩展程度越大。

西部生态移民跟踪调查--兼对西部扶贫战略的再思考

文章评述了近年西部生态移民方式变革的进步与局限。指出有效解决西部贫困暨生态恶化区域贫困及生态恶化的问题,最终绕不开"外向转移人口压力",建议适度改革现行以内部生态移民及整村推进开发扶贫为重点的扶贫战略,利用我国农业劳动力转移与教育发展大趋势,整合目前国家相关发展战略,多种措施有效卸载西部生态脆弱区的人口压力,从根本上解决西部贫困与生态问题。

高应力区大断面硐室维修加固支护技术

处于高应力区、采动影响、围岩软弱环境中的大断面硐室破坏现象严重,影响了矿井安全高效开采。以恒源煤矿Ⅱ62采区轨道下山绞车房为研究对象,通过钻孔窥视,探查巷道围岩破坏情况,给支护方案提供了依据。采用顶板组合式拉力分散型树脂与注浆全长锚固锚索支护+直墙岩体破碎段钢筋混凝土墙置换+锚索支护的综合支护技术,矿压观测结果表明,该支护方案能够有效控制高应力区大断面修复硐室的围岩变形;提出并实施的"新型组合式拉力分散型树脂与注浆全长锚固锚索"支护技术,能够实现普通锚索支护的高强度与注浆加固的联合支护,对提高巷道或硐室长期支护安全具有重要意义。

高地压巷道围岩加固支护技术研究

试验巷道位于断层影响带内,构造应力明显,且受到采动集中应力的影响,属于典型的高地压巷道。采用钻孔窥视手段对巷道围岩进行窥视探测,为巷道锚梁网支护设计提供重要参考。针对高地压巷道典型应力环境,设计了新型注浆结构,在不改变现有锚索锚固结构的同时,在自由段注浆,并使锚索由端锚变为全长锚固,提出了收集表面压力,并将其转移至深部的综合支护方法。现场观测结果表明,该支护方法能够有效控制类似环境下高地压软弱围岩巷道的围岩变形。

Stress-transfer characteristics of embedded fiber Bragg grating sensors

The shear lag theory is used to analyze the stress transfer from concrete matrix to FBG sensors based on that the FBG sensor and the concrete matrix are composite. The stress transfer formula and the coefficient are obtained. The experiments prove that the theoretical results of the stress transfer by the stress transfer formula are in well agreement with the experimental data.

Material transfer behavior of AgTiB_2 contact under different contact forces and electrode gaps

To disclose the effect of contact force and electrode gap on the material transfer behavior of Ag-based contact material, arc-erosion tests of the Ag-4wt.%TiB2 contact material were performed for 5000 operations at 24 V/16 A under resistive load on an electric contact material testing system. The arc energy and arc duration were investigated, the surface morphologies of eroded anode and cathode were characterized, the mass changes after arc-erosion tests were determined, and the material transfer behavior was discussed as well. The results show that contact force has a significant effect on the arc energy, arc duration and erosion morphology, but has no impact on the material transfer mode. However, electrode gap not only influences the arc energy, arc duration and surface morphology, but also changes the material transfer mode. At 1 mm, the material transfers from anode to cathode. Nevertheless, an opposite mode presents at 4 mm, which is from cathode to anode.

A gene encoding AtPIP5K2 may be involved in regulating the sensitivity to osmotic stress

One mutant line eto with salt tolerance was screened from a T-DNA insertion mutant collection of Arabidopsis thaliana. In addition to a reduced rate of seed germination, NaCl and ABA also inhibited the growth and the greening of cotyledons of wild-type seedlings, but not the eto mutant. TAIL-PCR analysis showed that T-DNA tag insertion in the eto was located at nucleotide 27,502 in BAC F3M18, upstream （at position -487 relative to the translation initiation codon） of gene At lg77740 （encoding a putative phosphatidylinositol-4-phosphate 5-kinase, AtPIP5K2）. This inserted mutation cosegregated closely with the eto phenotype, Another analysis not only indicated that AtPIP5K2 transcript is expressed predominantly in roots and rosette leaves, but also showed the T-DNA insertion resulted higher accumulation of the AtPIP5K2 in eto mutant plants and did not influenced the expression of the upstream At lg77730 gene. This change may play an essential role in the tolerance of eto mutant plant to the osmotic stress.

The Pressure Gradient Elastic Wave： Energy Transfer Process for Compressible Fluids with Pressure Gradient

The temperature separation was discovered inside the short vortex chamber （H/D = 0.18）. Experiments revealed that the highest temperature of the periphery was 465 ℃, and the lowest temperature of the central zone was -45 ℃ （the compressed air was pumped into the chamber at room temperature）. The objective of this paper is to proof that this temperature separation effect cannot be explained by conventional heat transfer processes. To explain this phenomenon, the concept of PGEW （Pressure Gradient Elastic Waves） is proposed. PGEW are kind of elastic waves, which operate in compressible fluids with pressure gradients and density fluctuations. The result of PGEW propagation is a heat transfer from area of low pressure to high pressure zone. The physical model of a gas in a strong field of mass forces is proposed to substantiate the PGEW existence. This physical model is intended for the construction of a theory of PGEW. Understanding the processes associated with the PGEW permits the possibility of creating new devices for energy saving and low potential heat utilization, which have unique properties.

Distribution characteristics and impact on pump＇s efficiency of hydro-mechanical losses of axial piston pump over wide operating ranges

A novel performance model of losses of pump was presented,which allows an explicit insight into the losses of various friction pairs of pump.The aim is to clarify that to what extent the hydro-mechanical losses affect efficiency,and to further gain an insight into the variation and distribution characteristics of hydro-mechanical losses over wide operating ranges.A good agreement is found in the comparisons between simulation and experimental results.At rated speed,the hydro-mechanical losses take a proportion ranging from 87% to 89% and from 68% to 97%,respectively,of the total power losses of pump working under 5 MPa pressure conditions,and 13% of full displacement conditions.Furthermore,within the variation of speed ranging from 48% to 100% of rated speed,and pressure ranging from 14% to 100% of rated pressure,the main sources of hydro-mechanical losses change to slipper swash plate pair and valve plate cylinder pair at low displacement conditions,from the piston cylinder pair and slipper swash plate pair at full displacement conditions.Besides,the hydro-mechanical losses in ball guide retainer pair are found to be almost independent of pressure.The derived conclusions clarify the main orientations of efforts to improve the efficiency performance of pump,and the proposed model can service for the design of pump with higher efficiency performance.

Numerical investigation on gas flow heat transfer and pressure drop in the shell side of spiral-wound heat exchangers

As a critical facility,spiral-wound heat exchanger was(SWHE)has the been widely used in many industrial applications.boundary A computational fluid dynamics(CFD)model employed with smallest periodic element results and periodic conditions to examine around the the characteristics tube of the shell side of SWHE.Numerical simulation show that the heat transfer coefficients and initially mean increase absolute and subsequently decrease simulated 5%with heat radial angle because of the influence measured of backflow turbulent separation.nitrogen The deviation between is transfer coefficients and values for methane,drop,ethane,and are a mixture(methane/ethane)within when mean Reynolds number is over is 30000.For the pressure the simulated results values smaller than the measured values,and the absolute on deviation within 9%.Numerical simulation also tubes indicate that the pressure drop the and heat of transfer coefficients angle the shell side and of SWHE heat decrease as the winding the angle of the increases.Nusselt Considering effect winding on pressure drops transfer coefficients,modified correlations of_=0.308Re^(0.64)Pr^(0.36)(1+sin)^(1.38 )and friction factor f_=0.435Re^(-0.133)(sin)^(-0.36),are proposed.Comparing Nu number with the experimental data,the maximum deviations for heat transfer coefficients and pressure drops are less than 5%and11%respectively.

Turbulent Convective Heat Transfer of Methane at Supercritical Pressure in a Helical Coiled Tube

The heat transfer of methane at supercritical pressure in a helically coiled tube was numerically investigated using the Reynolds Stress Model under constant wall temperature. The effects of mass flux （G）, inlet pressure （Pin） and buoyancy force on the heat transfer behaviors were discussed in detail. Results show that the light fluid with higher temperature appears near the inner wall of the helically coiled tube. When the bulk temperature is less than or approach to the pscudocritical temperature （Tpc）, the combined effects of buoyancy force and centrifugal force make heavy fluid with lower temperature appear near the outer-right of the helically coiled tube. Beyond the Tpc, the heavy fluid with lower temperature moves from the outer-right region to the outer region owing to the centrifugal force. The buoyancy force caused by density variation, which can be characterized by Gr/Re3 and Gr/Re2.7, enhances the heat transfer coefficient （h） when the bulk temperature is less than or near the T~, and the h expe- riences oscillation due to the buoyancy force. The oscillation is reduced progressively with the increase of G. Moreover, h reaches its peak value near the Tpv. Higher G could improve the heat transfer performance in the whole temperature range. The peak value ofh depends on Pin. A new correlation was proposed for methane at su- percritical pressure convective heat transfer in the helical tube, which shows a good agreement with the present simulated results.