基于MATLAB的两级NW型风电齿轮箱传动系统参数多目标优化

针对由两级NW型行星轮系串联构成的一种新型兆瓦级风电齿轮箱传动系统,建立体积最小和效率最高的多目标优化数学模型。设定两级行星轮数量,并形成5种方案。借助MATLAB工具成功求解并对比5种方案结果,得出结论:当两级行星轮数量为3时,该方案达到最优状态,符合常见的行星轮数量要求。

基于Ag NWs/棉织物柔性压力传感器的制备及性能

针对柔性传感器制造工艺繁琐、成本昂贵等缺点,以银纳米线(Ag NWs)为导电物质,以棉织物为弹性基体,采用反复浸渍的方法制备出一类具有良好弹性的柔性压力传感器。实验结果显示,棉织物经Ag NWs浸渍后,Ag NWs可均匀包裹在棉纤维上,形成有效的导电网络,且具有一定的柔性。此外Ag NWs的含量越高,Ag NWs对织物的导电性越好。在5次浸渍后,Ag NWs/棉织物内部形成稳定的导电网状结构,其检测灵敏度可达到3.36 kPa^(-1)。在压力为1.74~7.60 kPa范围内,此传感器对压力的响应和松弛时间均为50 ms。证明所研制的压力传感器具有较好的传感性能,可以作为一种优良的柔性压力传感器使用。

Short-term Association of Meteorological Elements on COVID-19 Pandemic in a Semi-arid City of Northwest China,2021-2022

The coronavirus disease 2019(COVID-19)outbreak in late 2019 significantly impacted global health.The virus’s rapid spread,with its long incubation period and high infection level,caused substantial disruption to regular social frameworks,production,and lifestyles^([1]).COVID-19 is primarily transmitted through close contact,long-range contaminants,and airborne routes.

Climate and topography regulate the spatial pattern of soil salinization and its effects on shrub community structure in Northwest China

Soil salinization may affect biodiversity and species composition,leading to changes in the plant community structure.However,few studies have explored the spatial pattern of soil salinization and its effects on shrub community structure at the ecosystem scale.Therefore,we conducted a transect sampling of desert shrublands in Northwest China during the growing season(June–September)in 2021.Soil salinization(both the degree and type),shrub community structure(e.g.,shrub density and height),and biodiversity parameters(e.g.,Simpson diversity,Margalf abundance,Shannon-Wiener diversity,and Pielou evenness indices)were used to assess the effects of soil salinization on shrub community structure.The results showed that the primary degree of soil salinization in the study area was light salinization,with the area proportion of 69.8%.Whereas the main type of soil salinization was characterized as sulfate saline soil,also accounting for 69.8%of the total area.Notably,there was a significant reduction in the degree of soil salinization and a shift in the type of soil salinization from chloride saline soil to sulfate saline soil,with an increase in longitude.Regional mean annual precipitation(MAP),mean annual evapotranspiration(MAE),elevation,and slope significantly contributed to soil salinization and its geochemical differentiation.As soil salinization intensified,shrub community structure displayed increased diversity and evenness,as indicated by the increases in the Simpson diversity,Shannon-Wiener diversity,and Pielou evenness indices.Moreover,the succulent stems and leaves of Chenopodiaceae and Tamaricaceae exhibited clear advantages under these conditions.Furthermore,regional climate and topography,such as MAP,MAE,and elevation,had greater effects on the distribution of shrub plants than soil salinization.These results provide a reference for the origin and pattern of soil salinization in drylands and their effects on the community structure of halophyte shrub species.

Evaluating the Impact of the Universal Test and Treat Strategy on the Survival of Patients in the Northwest Region of Cameroon

Introduction: The main outcome of efficiently implemented universal test and treat (UTT) program is improved survival. UTT implementation has been ongoing in Cameroon since 2016 but evaluation data are scarce. This study aims to assess the survival of antiretroviral therapy (ART) patients initiated under UTT in Northwest region of Cameroon. Methods: This retrospective cohort study included HIV-positive patients initiated in 2016 at 27 purposefully selected sites and followed until 2021. Data was anonymously abstracted from ART registers and patients’ charts. Kaplan-Meier survival estimates and Cox model were used to compare the survival of patients initiated under UTT with those initiated otherwise, using stata version 14.0. Results: In total, 2490 HIV-positive patients (median age 42.7 years, 94.7% adults, and 69.0% female) participated in the study. Of 1389 patients with viral load (VL) test results, 55% were initiated on ART late. The VL suppression rate of patients initiated late and those initiated early were similar. During follow-up, 1020 (40.9%) participants censored. The survival curves of patients initiated early on ART and those initiated late were similar during the first 2.5 years of follow-up but significantly (p Conclusions: This study confirms the expected impact of UTT. Programs only need to close existing implementation gaps along the critical pathways (diagnosis and treatment) of UTT, focusing more on males.

Spatiotemporal variability of rain-on-snow events in the arid region of Northwest China

Rain-on-snow(ROS)events involve rainfall on snow surfaces,and the occurrence of ROS events can exacerbate water scarcity and ecosystem vulnerability in the arid region of Northwest China(ARNC).In this study,using daily snow depth data and daily meteorological data from 68 meteorological stations provided by the China Meteorological Administration National Meteorological Information Centre,we investigated the spatiotemporal variability of ROS events in the ARNC from 1978 to 2015 and examined the factors affecting these events and possible changes of future ROS events in the ARNC.The results showed that ROS events in the ARNC mainly occurred from October to May of the following year and were largely distributed in the Qilian Mountains,Tianshan Mountains,Ili River Valley,Tacheng Prefecture,and Altay Prefecture,with the Ili River Valley,Tacheng City,and Altay Mountains exhibiting the most occurrences.Based on the intensity of ROS events,the areas with the highest risk of flooding resulting from ROS events in the ARNC were the Tianshan Mountains,Ili River Valley,Tacheng City,and Altay Mountains.The number and intensity of ROS events in the ARNC largely increased from 1978 to 2015,mainly influenced by air temperature and the number of rainfall days.However,due to the snowpack abundance in areas experiencing frequent ROS events in the ARNC,snowpack changes exerted slight impact on ROS events,which is a temporary phenomenon.Furthermore,elevation imposed lesser impact on ROS events in the ARNC than other factors.In the ARNC,the start time of rainfall and the end time of snowpack gradually advanced from the spring of the current year to the winter of the previous year,while the end time of rainfall and the start time of snowpack gradually delayed from autumn to winter.This may lead to more ROS events in winter in the future.These results could provide a sound basis for managing water resources and mitigating related disasters caused by ROS events in the ARNC.

Ecological Network Resilience of Shiyang River Basin: An Arid Inland Watershed of Northwest China

Due to the uncertainties posed by climate change,resilience has become an increasingly important variable for evaluating regional ecosystem stability.The assessment of Ecological Network Resilience(ENR)is crucial for establishing mitigation strategies and sustainable socioeconomic development in arid regions.Shiyang River Basin is an arid watershed in Northwest China with complex characteristics,its ENR and spatial differentiation characteristics in 2020 were investigated in this work based on the Complex Adaptive System(CAS)theory.The results indicated that the mean Ecological Network Resilience Index(ENRI)value for the Shiyang River Basin was 0.390 in 2020,and the mean values in the southern mountainous,middle oasis,and northern desert regions of the basin were 0.598,0.461,and 0.237,respectively,demonstrating evident spatial differences.Additionally,the ENR of the basin exhibited distinct distribution characteristics across different dimension,whereas the trend of the integrated ENR of the basin was consistent with that of elemental,structural,and functional resilience,indicating the constructed three-region ENR model based on the logical relationship of element-structure-function was suitable for evaluation of the ENR in arid inland river watersheds.Furthermore,strategies for enhancing regional ENR were proposed from the perspective of adapting to climate change.

Predicting changes in the suitable habitats of six halophytic plant species in the arid areas of Northwest China

In the context of changes in global climate and land uses,biodiversity patterns and plant species distributions have been significantly affected.Soil salinization is a growing problem,particularly in the arid areas of Northwest China.Halophytes are ideal for restoring soil salinization because of their adaptability to salt stress.In this study,we collected the current and future bioclimatic data released by the WorldClim database,along with soil data from the Harmonized World Soil Database(v1.2)and A Big Earth Data Platform for Three Poles.Using the maximum entropy(MaxEnt)model,the potential suitable habitats of six halophytic plant species(Halostachys caspica(Bieb.)C.A.Mey.,Halogeton glomeratus(Bieb.)C.A.Mey.,Kalidium foliatum(Pall.)Moq.,Halocnemum strobilaceum(Pall.)Bieb.,Salicornia europaea L.,and Suaeda salsa(L.)Pall.)were assessed under the current climate conditions(average for 1970-2000)and future(2050s,2070s,and 2090s)climate scenarios(SSP245 and SSP585,where SSP is the Shared Socio-economic Pathway).The results revealed that all six halophytic plant species exhibited the area under the receiver operating characteristic curve values higher than 0.80 based on the MaxEnt model,indicating the excellent performance of the MaxEnt model.The suitability of the six halophytic plant species significantly varied across regions in the arid areas of Northwest China.Under different future climate change scenarios,the suitable habitat areas for the six halophytic plant species are expected to increase or decrease to varying degrees.As global warming progresses,the suitable habitat areas of K.foliatum,S.salsa,and H.strobilaceum exhibited an increasing trend.In contrast,the suitable habitat areas of H.glomeratus,S.europaea,and H.caspica showed an opposite trend.Furthermore,considering the ongoing global warming trend,the centroids of the suitable habitat areas for various halophytic plant species would migrate to different degrees,and four halophytic plant species,namely,S.salsa,H.strobilaceum,H.glomeratus,and H.capsica,would migrate to higher latitudes.Temperature,precipitation,and soil factors affected the possible distribution ranges of these six halophytic plant species.Among them,precipitation seasonality(coefficient of variation),precipitation of the warmest quarter,mean temperature of the warmest quarter,and exchangeable Na+significantly affected the distribution of halophytic plant species.Our findings are critical to comprehending and predicting the impact of climate change on ecosystems.The findings of this study hold significant theoretical and practical implications for the management of soil salinization and for the utilization,protection,and management of halophytes in the arid areas of Northwest China.

NWES in brief

China’s reusable carrier rocket completes first 10-km VTOL test China’s reusable carrier rocket successfully completed a 10-km vertical take-off and landing(VTOL)flight test at the Jiuquan Satellite Launch Center in northwest China on June 23.

Effect of CO_(2)flooding in an oil reservoir with strong bottom-water drive in the Tahe Oilfield,Tarim Basin,Northwest China

The dissolution and diffusion of CO_(2)in oil and water and its displacement mechanism were investigated by laboratory experiment and numerical simulation for Block 9 in the Tahe oilfield,a sandstone oil reservoir with strong bottom-water drive in Tarim Basin,Northwest China.Such parameters were analyzed as solubility ratio of CO_(2)in oil,gas and water,interfacial tension,in-situ oil viscosity distribution,remaining oil saturation distribution,and oil compositions.The results show that CO_(2)flooding could control water coning and increase oil production.In the early stage of the injection process,CO_(2)expanded vertically due to gravity differentiation,and extended laterally under the action of strong bottom water in the intermediate and late stages.The CO_(2)got enriched and extended at the oil-water interface,forming a high interfacial tension zone,which inhibited the coning of bottom water to some extent.A miscible region with low interfacial tension formed at the gas injection front,which reduced the in-situ oil viscosity by about 50%.The numerical simulation results show that enhanced oil recovery(EOR)is estimated at 5.72%and the oil exchange ratio of CO_(2)is 0.17 t/t.

Comprehensive applicability evaluation of four precipitation products at multiple spatiotemporal scales in Northwest China

Precipitation plays a crucial role in the water cycle of Northwest China.Obtaining accurate precipitation data is crucial for regional water resource management,hydrological forecasting,flood control and drought relief.Currently,the applicability of multi-source precipitation products for long time series in Northwest China has not been thoroughly evaluated.In this study,precipitation data from 183 meteorological stations in Northwest China from 1979 to 2020 were selected to assess the regional applicability of four precipitation products(the fifth generation of European Centre for Medium-Range Weather Forecasts(ECMWF)atmospheric reanalysis of the global climate(ERA5),Global Precipitation Climatology Centre(GPCC),Climatic Research Unit gridded Time Series Version 4.07(CRU TS v4.07,hereafter CRU),and Tropical Rainfall Measuring Mission(TRMM))based on the following statistical indicators:correlation coefficient,root mean square error(RMSE),relative bias(RB),mean absolute error(MAE),probability of detection(POD),false alarm ratio(FAR),and equitable threat score(ETS).The results showed that precipitation in Northwest China was generally high in the east and low in the west,and exhibited an increasing trend from 1979 to 2020.Compared with the station observations,ERA5 showed a larger spatial distribution difference than the other products.The overall overestimation of multi-year average precipitation was approximately 200.00 mm and the degree of overestimation increased with increasing precipitation intensity.The multi-year average precipitation of GPCC and CRU was relatively close to that of station observations.The trend of annual precipitation of TRMM was overestimated in high-altitude regions and the eastern part of Lanzhou with more precipitation.At the monthly scale,GPCC performed well but underestimated precipitation in the Tarim Basin(RB=-4.11%),while ERA5 and TRMM exhibited poor accuracy in high-altitude regions.ERA5 had a large bias(RB≥120.00%)in winter months and a strong dispersion(RMSE≥35.00 mm)in summer months.TRMM showed a relatively low correlation with station observations in winter months(correlation coefficients≤0.70).The capture performance analysis showed that ERA5,GPCC,and TRMM had lower POD and ETS values and higher FAR values in Northwest China as the precipitation intensity increased.ERA5 showed a high capture performance for small precipitation events and a slower decreasing trend of POD as the precipitation intensity increased.GPCC had the lowest FAR values.TRMM was statistically ineffective for predicting the occurrence of daily precipitation events.The findings provide a reference for data users to select appropriate datasets in Northwest China and for data developers to develop new precipitation products in the future.

基于Cu NWs/Ag NWs/棉纺织品的疏水性可穿戴压力传感器

为提升可穿戴传感器的传感性能,拓宽其应用范围,降低其制备成本,采用水热法制备铜纳米线(Cu NWs)墨水,多元醇法制备银纳米线(Ag NWs)墨水,并将棉纺织品依次浸渍到Cu NWs墨水与Ag NWs墨水中,制备Cu NWs/Ag NWs/棉纺织品传感器;研究Ag NWs浓度对传感器电学性质以及疏水性质的影响,并通过浸渍-干燥次数调控实现Cu NWs/Ag NWs/棉纺织品微观形貌以及传感器性能的优化。研究表明,Cu NWs/Ag NWs/棉纺织品传感器具有优异的疏水性,其水接触角高达147°;Ag NWs浓度的增大有利于提高Cu NWs/Ag NWs/棉纺织品的导电能力,但对其疏水性影响不大;当浸渍次数为3次时,Cu NWs/Ag NWs/棉纺织品内部形成稳固、优异的导电网络,传感器性能最优,其灵敏度高达5.64 kPa^(-1),检测范围为1.5~20 kPa,响应恢复时间分别为300、200 ms,且对微笑、握拳、触摸等行为显示出规律的电流响应。实验证明该传感器在健康监测与水下运动检测领域有着良好的应用前景。

BTO NWs/PVDF柔性复合薄膜的制备及其压电性能研究

该文通过两步水热法制备了钛酸钡纳米线(BTO NWs),采用旋涂法与聚偏氟乙烯(PVDF)复合制备BTO NWs/PVDF复合薄膜。系统地研究了水热反应中不同NaOH浓度、不同反应时间及不同BTO NWs掺杂量对BTO NWs/PVDF复合薄膜压电输出性能的影响,并与商用钛酸钡纳米球(BTO NPs)制备的BTO NPs/PVDF复合薄膜进行了压电性能对比。结果表明,当NaOH浓度为10 mol/L,反应时间为10 h时,BTO NWs/PVDF复合薄膜开路电压和短路电流分别可达5.42 V和1.81μA。当BTO NWs掺杂量(质量分数)为20%时,复合压电薄膜的开路电压可达9.34 V,短路电流可达2.15μA,分别是BTO NPs/PVDF复合薄膜输出电压和电流的1.92倍和1.49倍。当负载电阻值为5 MΩ时,BTO NWs/PVDF复合薄膜输出功率可达1.44μW。经过4000次循环敲击测试,BTO NWs/PVDF复合薄膜表现出良好的机械稳定性,其有望在自供电器件、柔性可穿戴电子设备等领域得到广泛应用。

The Concurrent Record-breaking Rainfall over Northwest India and North China in September 2021

Extremely heavy rainfall occurred over both Northwest India and North China in September 2021.The precipitation anomalies were 4.1 and 6.2 times interannual standard deviation over the two regions,respectively,and broke the record since the observational data were available,i.e.,1901 for India and 1951 for China.In this month,the Asian uppertropospheric westerly jet was greatly displaced poleward over West Asia,and correspondingly,an anomalous cyclone appeared over India.The anomalous cyclone transported abundant water vapor into Northwest India,leading to the heavy rainfall there.In addition,the Silk Road pattern,a teleconnection pattern of upper-level meridional wind over the Eurasian continent and fueled by the heavy rainfall in Northwest India,contributed to the heavy rainfall in North China.Our study emphasizes the roles of atmospheric teleconnection patterns in concurrent rainfall extremes in the two regions far away from each other,and the occurrence of rainfall extremes during the post-or pre-monsoon period in the northern margins of monsoon regions.

基于动态性能分析的风电增速箱NW型行星齿轮综合修形方法

风电增速箱是风力发电系统的关键部件,其传动性能的优劣直接关系到风电系统能否可靠运行。NW型行星齿轮因其具有结构紧凑、承载能力及传递功率范围大等优点被应用于风电增速箱中,但NW型行星齿轮的齿面易发生载荷集中现象、传动误差较大,从而通常会使齿轮的使用寿命缩短并且使它们在风力发电机组中的广泛应用受到限制。齿轮修形常被用来改善齿轮传动性能,然而,传统修形技术尚无法有效地解决上述问题。为此,同时综合考虑了齿轮单位长度载荷以及传递误差对传动性能的影响,结合齿向修形和齿廓修形的优势,并基于接触斑点、啮合错位量等仿真分析结果,提出了一种兼顾降低传动误差与改善齿面集中载荷的齿轮综合修形方法。应用该方法对NW型行星齿轮内外啮合齿轮副分别进行修形,并对修形效果进行了仿真验证。分析结果表明,相比于未修形的状态,内外啮合齿轮副最大单位长度载荷分别降低了17.21%、24.16%;传动误差分别降低了22.64%、35.23%,可见综合修形同时改善了齿轮传动误差和齿面载荷分布,从而提高了风电增速箱中齿轮的传动性能和使用寿命,对风力发电的发展具有重要研究意义。

Correction to:Modelling the response of larch growth to age,density,and elevation and the implications for multifunctional management in northwest China

In Table 3 of the published version,“Parameters fi tted for tree height and DBH growth models of Eq.(6)”,the parameters letter mismatched the corresponding values.Hence,the authors regret that this may lead to mistakes in the tree height and DBH simulation based on the model Eq.(6).The correct Table 3 with exact parameter values is listed as follow.

Surface Processes Driving Intracontinental Basin Subsidence in the Context of India–Eurasia Collision:Evidence from Flexural Subsidence Modeling of the Cenozoic Southern Tarim Basin along the West Kunlun Foreland,NW Tibetan Plateau

The India–Eurasia collision has produced a number of Cenozoic deep intracontinental basins,which bear important information for revealing the far-afield responses to the remote collision.Despite their significance,their subsiding mechanism remains the subject of debate,with end-member models attributing it to either orogenic or sedimentary load.In this study,we conduct flexural subsidence modeling with a two-dimensional finite elastic plate model on the Hotan-Mazatagh section along the southern Tarim Basin,which defines a key region in the foreland of the West Kunlun Orogen,along the NW margin of the Tibetan Plateau.The modeling results indicate that the orogenic load of West Kunlun triggers the southern Tarim Basin to subside by up to less than ~6 km,with its impact weakening towards the basin interiors until ~230 km north from the Karakax fault.The sedimentary load,consisting of Cenozoic strata,forces the basin to subside by ~2 to~7 km.In combination with the retreat of the proto-Paratethys Sea and the paleogeographic reorganization of the Tarim Basin,we propose that surface processes,in particular a shift from an exorheic to an endorheic drainage system associated with the consequent thick sedimentary load,played a decisive role in forming deep intracontinental basins in the context of the India-Eurasia collision.

Determinants of Smallholder Farmers Adoption of Acacia decurrens in Northwest Ethiopia

Planting a fast-growing multipurpose Acacia decurrens (AD) tree is one of the climate-smart agricultural practices that have been promoted in Ethiopia, which is widely practiced and an important livelihood strategy in Awi zone. However, the extent of its adoption varies considerably among households in the study area. This study investigated the determinants of intensity of adoption of AD among 385 randomly selected rural households in Awi Zone. Data were gathered using a cross-sectional household survey. Descriptive statistics and Two-limit Tobit model were employed for data analysis. The result of the study shows that on average the intensity of adoption of AD was 0.43 (43% of the total cropland area), though majority of the farmers (48.8%) belong to low level of adoption. The result of the analysis shows that being male, educational level, access to seedling, experience in growing the tree, extension contact has positive and significant relationship with the intensity of adoption. Age of head of household, land holding size, livestock holding size, soil fertility status, disease emergence and road distance have negative and significant influence on intensity of adoption. These suggest that expanding road infrastructure, education, access to seedling, secure land property right, disease management, and provision of extension services related to the AD can also improve smallholder farmers’ intensity of AD adoption. The generated information provides a picture of the study area’s situation to the attention of policy makers, development practitioners and institutional service providers to formulate a better policy intervention to sustain smallholder farmers’ AD plantation.

Long-term improvements in water conservation functions at Qilian Mountain National Park, northwest China

Water conservation is one of the most important ecosystem functions.This study uses the InVEST model to examine the water conservation function of the Qilian Mountain National Park(QMNP),an important water supply area in northwest China.We analyzed the spatiotemporal water conservation patterns of QMNP from 1988 to 2019.It showed that the water conservation capacity in QMNP has increased over the past 32 years,reaching a peak of 6.495×108 m3 in 2019.The area with an increased water conservation capacity is 12 times larger than the area with a reduced capacity.We also examined how climatic,land-use,vegetation coverage,and topographical factors influence water conservation functions.We found that precipitation is the main climatic factor in water conservation.The water conservation function also varies with land-cover type,with forests having the highest capacity,followed by grasslands.Lastly,topographical factors,including altitude and slope,also shape the spatial patterns of water conservation functions in QMNP.

西北地区冠心病患者ApoE基因多态性分布研究以及对他汀类药物使用的指导意义

目的探讨我国西北地区冠心病患者ApoE基因多态性分布情况。方法选取西安交通大学第一附属医院冠心病治疗患者2388例,检测ApoE的基因型,统计基因型及等位基因分布特征,并对比国内外其他地区基因型及等位基因分布差异。结果E3E3、E3E4、E2E3、E2E4、E4E4、E2E2,分别占患者总数的70.31%、15.20%、11.93%、1.30%、0.75%、0.50%。检测出ApoE E2、E3及E4等位基因频率分别为7.12%、83.88%、9.00%。不同性别、年龄冠心病患者之间ApoE基因型及等位基因分布差异均无统计学意义;不同国家和地区ApoE基因型及等位基因分布差异均具有统计学意义。结论西北地区冠心病患者ApoE基因型主要以E3E3、E3E4为主,等位基因以E3为主,有助于目前血脂正常的人群预测血脂异常风险,从而早期通过调节饮食和生活方式来控制血脂,预防或延缓心脑血管疾病的发生。同时也可为患者合理使用他汀类药物提供一定的参考依据。