西宁方言元音的高化、齿化、单化和鼻化

本文讨论西宁方言元音的高化、齿化、单化和鼻化。想必对西宁方言音位系统特点的认识,对西宁方音演变的现状,对当前正在进行的方言资源库的建设,也具有一定的现实意义,对研究西北方音史,甚或对汉语语音史的研究都具有重大的意义。

晋城市城市化进程中语言的变迁——普通话影响下元音高化链条中断原因的探讨

晋城市区及郊区方言止蟹两摄两类合口字在过去的一百年间存在一个元音高化的推链式链条,这个链条的推动力在20世纪后期中断了。中断的原因主要是晋城人的语言态度及晋城人对普通话的模仿;另外,晋城后期方言音系中出现的韵基部位和谐与唇状和谐也是一个内在因素。

梗摄元音的前高化道路研究——从东南方言文白异读和汉越音的异读来探讨

梗摄元音在东南方言中是一个a、e、i、 的系统，其中a、e、i是同源层次，这一点可以从汉越音的梗摄元音得到印证，a是异源层次，i、3保存于文读音，而a（e）保存于白读音。汉越音保存了一个完整的梗摄异读系统，体现出了梗摄a—e—i的前高化演变道路，而且a、e元音都保存在古汉越语中，是相对于i元音的白读音。梗摄韵母a—e的演变历程开始于上古时期，而梗摄前高化的历程，至少在中唐前就已经完成。

娄邵片湘语中假宕江梗摄主元音的后高化演变——兼谈假摄主元音后高化的动因

娄邵片湘语中不仅假摄主元音发生了后高化演变,宕摄、江摄和梗摄的主元音也发生了相同的演变。不同韵摄的主元音,先后沿着相同的路线演变,不会是受到其他韵摄的影响,是一种自主的演变。

论宁波方言和苏州方言前高元音的区别特征——兼谈高元音继续高化现象

本文利用发音生理和声学语音材料讨论吴语宁波方言和苏州方言的前高元音的区别特征。文章发现宁波话3个前高元音[i y Y]拥有相似的舌位,其区别主要来自于唇型不同,其中[i]为展唇、[y]为水平撮唇、[Y]为垂直撮唇;苏州话4个前高元音[i y I Y]之间音位对立的区别特征则是[擦音性],苏州[I Y]在声学语音上可与一般语言中的前高元音[i y]类比,而苏州[i y]则是带有强摩擦的元音。结合语音学分析与历史演变脉络,文章认为两地前高元音之间这种强标记性的音位对立格局的形成来源于高元音继续高化这一历史音变。

粤语、平话和南方民族语中的元音前高化现象

粤语和平话中的元音前高化音变现象非常突出,这一现象在南方少数民族语言中的中古汉借词中也有体现。发生前高化的元音来自中古的外转,并且都是长元音,由于i介音的影响而前高化。这一音变应是在南宋时期在古岭南汉语中发生,又通过借词进入民族语。

陕北晋语以高化为主的拉链式音变

中古许多韵摄今读在陕北晋语普遍存在着韵母元音的高化现象,包括果摄、假摄、遇摄、蟹摄、止摄、成摄、山摄,主要以三等字为主。其中果摄、假摄、成摄、山摄今读韵母元音的高化在所有方言点较一致,蟹止摄开口三四等、遇摄、止摄合口今读韵母元音的高化在不同方言点有不同特点。在音变的具体方式上,则表现为如杜家湾子洲等方言点一样的拉链式音变。

Recent advances in design of hydrogen evolution reaction electrocatalysts at high current density:A review

The electrolysis of water powered by renewable energy sources offers a promising method of"green hydrogen"production,which is considered to be at the heart of future carbon-neutral energy systems.In the past decades,researchers have reported a number of hydrogen evolution reaction(HER)electrocatalysts with activity comparable to that of commercial Pt/C,but most of them are tested within a small current density range,typically no more than 500 mA cm^(-2).To realize the industrial application of hydrogen production from water electrolysis,it is essential to develop high-efficiency HER electrocatalysts at high current density(HCD≥500 mA cm^(-2)).Nevertheless,it remains challenging and significant to rational design HCD electrocatalysts for HER.In this paper,the design strategy of HCD electrocatalysts is discussed,and some HCD electrocatalysts for HER are reviewed in seven categories(alloy,metal oxide,metal hydroxide,metal sulfide/selenide,metal nitride,metal phosphide and other derived electrocatalysts).At the end of this article,we also pro-pose some viewpoints and prospects for the future development and research directions of HCD electrocatalysts for HER.

A novel immiscible high entropy alloy strengthened via L1_(2)-nanoprecipitate

The low-cost Fe-Cu,Fe-Ni,and Cu-based high-entropy alloys exhibit a widespread utilization prospect.However,these potential applications have been limited by their low strength.In this study,a novel Fe_(31)Cu_(31)Ni_(28)Al_(4)Ti_(3)Co_(3) immiscible high-entropy alloy(HEA)was developed.After vacuum arc melting and copper mold suction casting,this HEA exhibits a unique phase separation microstructure,which consists of striped Cu-rich regions and Fe-rich region.Further magnification of the striped Cu-rich region reveals that it is composed of a Cu-rich dot-like phase and a Fe-rich region.The aging alloy is further strengthened by a L1_(2)-Ni_(3)(AlTi)nanoprecipitates,achieving excellent yield strength(1185 MPa)and uniform ductility(~8.8%).The differential distribution of the L1_(2) nanoprecipitate in the striped Cu-rich region and the external Fe-rich region increased the strength difference between these two regions,which increased the strain gradient and thus improved hetero-deformation induced(HDI)hardening.This work provides a new route to improve the HDI hardening of Fe-Cu alloys.

Research progress of permanent ferrite magnet materials

Permanent ferrite magnet materials are extensively employed due to their exceptional magnetic properties and cost-effectiveness.The fast development in electromobile and household appliance industries contributes to a new progress in permanent ferrite materials.This paper reviews the deveolpement and progress of permanent ferrite magnet industry in recent years.The emergence of new raw material,the advancement of perparation methods and manufacturing techniques,and the potential applications of permanent ferrite materials are introduced and discussed.Specifically,nanocrystallization plays a crucial role in achieving high performance at a low cost and reducing reliance on rare earth resources,and therefore it could be a promising development trendency.

Projected changes in extreme snowfall events over the Tibetan Plateau based on a set of RCM simulations

Extreme snowfall events over the Tibetan Plateau(TP)cause considerable damage to local society and natural ecosystems.In this study,the authors investigate the projected changes in such events over the TP and its surrounding areas based on an ensemble of a set of 21st century climate change projections using a regional climate model,RegCM4.The model is driven by five CMIP5 global climate models at a grid spacing of 25 km,under the RCP4.5 and RCP8.5 pathways.Four modified ETCCDI extreme indices-namely,SNOWTOT,S1mm,S10mm,and Sx5day-are employed to characterize the extreme snowfall events.RegCM4 generally reproduces the spatial distribution of the indices over the region,although with a tendency of overestimation.For the projected changes,a general decrease in SNOWTOT is found over most of the TP,with greater magnitude and better cross-simulation agreement over the eastern part.All the simulations project an overall decrease in S1mm,ranging from a 25%decrease in the west and to a 50%decrease in the east of the TP.Both S10mm and Sx5day are projected to decrease over the eastern part and increase over the central and western parts of the TP.Notably,S10mm shows a marked increase(more than double)with high cross-simulation agreement over the central TP.Significant increases in all four indices are found over the Tarim and Qaidam basins,and northwestern China north of the TP.The projected changes show topographic dependence over the TP in the latitudinal direction,and tend to decrease/increase in low-/high-altitude areas.

Enhancing selectivity in acidic CO_(2)electrolysis:Cation effects and catalyst innovation

The electrochemical reduction of CO_(2)(eCO_(2)R)under ambient conditions is crucial for reducing carbon emissions and achieving carbon neutrality.Despite progress with alkaline and neutral elec-trolytes,their efficiency is limited by(bi)carbonates formation.Acidic media have emerged as a solution,addressing the(bi)carbonates challenge but introducing the issue of the hydrogen evolu-tion reaction(HER),which reduces CO_(2)conversion efficiency in acidic environments.This review focuses on enhancing the selectivity of acidic CO_(2)electrolysis.It commences with an overview of the latest advancements in acidic CO_(2)electrolysis,focusing on product selectivity and electrocatalytic activity enhancements.It then delves into the critical factors shaping selectivity in acidic CO_(2)elec-trolysis,with a special emphasis on the influence of cations and catalyst design.Finally,the research challenges and personal perspectives of acidic CO_(2)electrolysis are suggested.

Global CO_(2)concentration change induced by“trigger-connectors”model,especially since about 24 Ma?A preliminary hypothesis

Background,aim,and scope The tectonic uplift of the Cenozoic Tibetan Plateau has produced a chain effect,which is an excellent location for Earth system science research,and its uplift process,mechanism and environmental effects are the hot spot and frontier of the current research.The“Tibetan Plateau uplift-weathering-CO_(2)concentration-global climate change”model was put forward by Raymo and Ruddiman to interpret the Late Cenozoic climate change.However,there are still some questions suspended,such as does the weathering of the Tibetan Plateau have the ability to control the global climate?How to explain the modern-like global CO_(2)concentration starting at about 24 Ma?Here,a short space was taken to present a brainstorm about the above questions on account of existing geological pieces of evidence.Materials and methods In this paper,we integrate the formation and evolution of the Yangtze River and Pearl River,the origin and development of the Asian inland aridification-monsoon system,the Cenozoic tectonic uplift process of the Tibetan Plateau,and the westerly winds to discuss and analyze the relationship between the Cenozoic CO_(2)concentration changes and the uplift of the Tibetan Plateau and why the CO_(2)concentration similar to the present was formed at about 24 Ma.Results Similar correspondence of the surface uplift history of Xizang,other global mountains,and the declining CO_(2)concentration could support the theory Tibetan Plateau weathering inf luences CO_(2)concentration.Starting from 24 Ma,the most important character was the uplift and erosion of Xizang and Himalaya,collaborating with Ocean Iron Fertilization(OIF)together as an entity to control the atmospheric CO_(2)concentration because the great Asian rivers,Asian monsoons,and westerlies connected Xizang and surrounded seas together through materials transportation.Discussion Paleogeographic reconstructions from 40 Ma to 20 Ma illustrate that the main topographic change occurred in the Andes,Cordillera orogenic belt,and Xizang.We comprise a comprehensive set of evidence from independent data,which correspond temporally with the tipping point(about 24 Ma)of the atmospheric CO_(2)and we noticed that modern-like Asia monsoon,inland aridity,Asian great rivers,and climate zone formed at about 24 Ma and also there are tectonic activities for the Andes and Rockies.We raised the possibility that the modern-like atmospheric CO_(2)concentration at about 24 Ma was caused by the above geological factors.Here the rivers,monsoon,and westerlies are termed as“connectors”.In addition,these Asian rivers originated from Xizang,the monsoon,and inner Asian aridification are strongly a function of the uplift and growth of Xizang,thus,Xizang here is named as“trigger”.The distinct character of“trigger-connectors”model is that this not only takes the monsoon,westerlies,and the global great rivers into consideration but also expands the range which inf luences atmospheric CO_(2)concentration,from local points to a vast area since about 24 Ma,such as from Tibetan Plateau to Asia,including surrounded seas,after about 24 Ma.However,because the opening of the Late Oligocene-Early Miocene Antarctic periphery straits is highly coincident with the onset of modern-like global atmospheric CO_(2)concentration,we are forced to consider that they also had a significant impact on the reduction of atmospheric CO_(2)concentrations at this time.Conclusions“Trigger-connectors”was put forward to explain the Cenozoic CO_(2)variation,especially modern-like global CO_(2)concentration since about 24 Ma.Recommendations and perspectives Here we use the“trigger-connectors”model to explain the formation of modern-like CO_(2)concentrations starting at about 24 Ma,but there are still some problems.The most important premise for the“trigger-connectors”model is the constructed Cenozoic CO_(2)concentration record is reliable,which is the foundation of our hypothesis.In the future,potential improvements should focus on topographic reconstructions of Xizang and the global mountains.Here we have concentrated on Xizang in the considered timeslices but still,pay less attention to other global orogenic belts.Collaborations with geologist experts in those regions could provide valuable feedback to evaluate their potential role of them in CO_(2)evolution.What is more,considerable progress may be achieved with the addition and consideration of more and new geological data.

Microstructure and Oxidation Behavior of ZrB_(2)-SiC Ceramics Fabricated by Tape Casting and Reactive Melt Infiltration

ZrB_(2)-based ceramics typically necessitate high temperature and pressure for sintering,whereas ZrB_(2)-SiC ceramics can be fabricated at 1500℃using the process of reactive melt infiltration with Si.In comparison to the conventional preparation method,reactive synthesis allows for the more facile production of ultra-high temperature ceramics with fine particle size and homogeneous composition.In this work,ZrSi_(2),B4C,and C were used as raw materials to prepare ZrB_(2)-SiC via combination of tape casting and reactive melt infiltration herein referred to as ZBC ceramics.Control sample of ZrB_(2)-SiC was also prepared using ZrB_(2) and SiC as raw materials through an identical process designated as ZS ceramics.Microscopic analysis of both ceramic groups revealed smaller and more uniformly distributed particles of the ZrB_(2) phase in ZBC ceramics compared to the larger particles in ZS ceramics.Both sets of ceramics underwent cyclic oxidation testing in the air at 1600℃for a cumulative duration of 5 cycles,each cycle lasting 2 h.Analysis of the oxidation behavior showed that both ZBC ceramics and ZS ceramics developed a glassy SiO_(2)-ZrO_(2) oxide layer on their surfaces during the oxidation.This layer severed as a barrier against oxygen.In ZBC ceramics,ZrO_(2) is finely distributed in SiO_(2),whereas in ZS ceramics,larger ZrO_(2) particles coexist with glassy SiO_(2).The surface oxide layer of ZBC ceramics maintains a dense structure because the well-dispersed ZrO_(2) increases the viscosity of glassy SiO_(2),preventing its crystallization during the cooling.Conversely,some SiO_(2) in the oxide layer of ZS ceramics may crystallize and form a eutectic with ZrO_(2),leading to the formation of ZrSiO_(4).This leads to cracking of the oxide layer due to differences in thermal expansion coefficients,weakening its barrier effect.An analysis of the oxidation resistance shows that ZBC ceramics exhibit less increase in oxide layer thickness and mass compared to ZS ceramics,suggesting superior oxidation resistance of ZBC ceramics.

Microstructural evolution and mechanical properties of duplex-phase Ti6242 alloy treated by laser shock peening

The effects of laser shock peening(LSP)on the microstructural evolution and mechanical properties of the Ti6242 alloy,including the residual stress,surface roughness,Vickers microhardness,tensile mechanical response,and high-cycle fatigue properties,were studied.The results showed that the LSP induced residual compressive stresses on the surface and near surface of the material.The maximum surface residual compressive stress was−661 MPa,and the compressive-stress-affected depth was greater than 1000μm.The roughness and Vickers micro-hardness increased with the number of shocks,and the maximum hardness-affected depth was about 700μm after three LSP treatments.LSP enhanced the fraction of low-angle grain boundaries,changed the grain preferred orientations,and notably increased the pole density ofαphase on the near surface from 2.41 to 3.46.The surface hardness values of the LSP samples increased with the increase of the number of shocks due to work hardening,while the LSP had a limited effect on the tensile properties.The high-cycle fatigue life of the LSP-treated sample was significantly enhanced by more than 20%compared with that of the untreated sample,which was caused by the suppression of the initiation and propagation of fatigue cracks.

A study on the simulation of carbon and water fluxes of Dangxiong alpine meadow and its response to climate change

The alpine meadow ecosystem accounts for 27%of the total area of the Tibetan Plateau and is also one of the most important vegetation types.The Dangxiong alpine meadow ecosystem,located in the south-central part of the Tibetan Plateau,is a typical example.To understand the carbon and water fluxes,water use efficiency(WUE),and their responses to future climate change for the alpine meadow ecosystem in the Dangxiong area,two parameter estimation methods,the Model-independent Parameter Estimation(PEST)and the Dynamic Dimensions Search(DDS),were used to optimize the Biome-BGC model.Then,the gross primary productivity(GPP)and evapotranspiration(ET)were simulated.The results show that the DDS parameter calibration method has a better performance.The annual GPP and ET show an increasing trend,while the WUE shows a decreasing trend.Meanwhile,ET and GPP reach their peaks in July and August,respectively,and WUE shows a“dual-peak”pattern,reaching peaks in May and November.Furthermore,according to the simulation results for the next nearly 100 years,the ensemble average GPP and ET exhibit a significant increasing trend,and the growth rate under the SSP5–8.5 scenario is greater than that under the SSP2–4.5 scenario.WUE shows an increasing trend under the SSP2–4.5 scenario and a significant increasing trend under the SSP5–8.5 scenario.This study has important scientific significance for carbon and water cycle prediction and vegetation ecological protection on the Tibetan Plateau.

Application and optimization design of non-obstructive particle damping-phononic crystal vibration isolator in viaduct structure-borne noise reduction

The problems associated with vibrations of viaducts and low-frequency structural noise radiation caused by train excitation continue to increase in importance.A new floating-slab track vibration isolator-non-obstructive particle damping-phononic crystal vibration isolator is proposed herein,which uses the particle damping vibration absorption technology and bandgap vibration control theory.The vibration reduction performance of the NOPD-PCVI was analyzed from the perspective of vibration control.The paper explores the structure-borne noise reduction performance of the NOPD-PCVIs installed on different bridge structures under varying service conditions encountered in practical engineering applications.The load transferred to the bridge is obtained from a coupled train-FST-bridge analytical model considering the different structural parameters of bridges.The vibration responses are obtained using the finite element method,while the structural noise radiation is simulated using the frequency-domain boundary element method.Using the particle swarm optimization algorithm,the parameters of the NOPD-PCVI are optimized so that its frequency bandgap matches the dominant bridge structural noise frequency range.The noise reduction performance of the NOPD-PCVIs is compared to the steel-spring isolation under different service conditions.

2014年全国高职院校数量变化趋势及分类比较

随着高等职业教育的快速发展,我国高等职业院校数量已占据高等教育的半壁江山,在加快构建现代职业教育体系的背景下,保持并持续扩大高职院校数量规模对于实现这一目标具有重要意义。高等职业学校的数量,决定了高等职业教育的规模,了解中国高等职业院校整体在数量特征方面的发展态势和资源配置情况,有助于从整体上对高等教育宏观调控的把握。

陕北晋语果摄字的读音

果摄在陕北晋语的读音类型比较丰富,不同的类型往往分布在不同的地区。通过对这些类型的分析,可以看出如下演变特点:首先,从开合口之间的关系看,果摄一等在陕北晋语的演变表现出两种大的趋势:一种趋势为果摄开口一等向果摄合口一等演变,主要位于陕北晋语西部、北部,另外一种趋势为合口并入开口,这样的方言点主要位于陕北晋语东部和南部。果摄合口一等并入开口一等在陕北晋语应当是先从泥组开始,然后波及到帮组,接着再波及到精组、见系,最后才是端组。其次,与中古音值相比,陕北晋语果摄开口字的读音都不同程度地存在着高化和前化现象。