基于自适应ROI的轴承内圈高精度视觉尺寸检测

针对机器视觉轴承内圈侧面复杂形状尺寸检测精度低的问题,提出根据检测目标建立小面积感兴趣区域(Region of Interest,ROI)的自适应选取方法和基于Zernike矩的ROI亚像素级边缘提取方法,大幅提升了轴承内圈尺寸的检测精度。首先分别拍摄轴承内圈左侧与右侧轮廓图像,对图像进行预处理。在此基础上,通过角点检测融合像素扫描的方法实现自适应ROI选取,解决了因轴承内圈移动引起的小面积ROI边缘误判问题;使用Canny算子提取ROI的像素级边缘,再用改进的Zernike矩算法得到亚像素级边缘。最后,分别对ROI中提取的边缘进行最小二乘圆拟合和直线拟合,根据像素当量与视场间隔将图像中各尺寸转换为轴承内圈实际尺寸。实验结果表明:所提方法测量的标准不确定度低于0.005 mm,满足轴承尺寸高精度检测的要求,对于实现轴承检测的自动化有实际意义。

结合自适应阈值与动态ROI的地标线检测方法

基于机器视觉的地标线检测一直以来都是车间自主巡检机器人研究的重点和难点问题之一.针对检测过程中易受车间地面积水、光照不均以及油渍粉尘污染等环境因素的影响从而导致误检率、漏检率较高,难以满足工程实际需求的问题,本文提出了一种基于自适应阈值分割与动态感兴趣区域划分的车间地标线检测方法(AT-DROI),该方法以分块图像为基础,首先按照特定特征对子块进行搜索,并剔除其中的离群噪声点,然后将环境因子与采样点相结合计算出特征颜色的双门限阈值,最后利用粗细粒度掩膜抑制特征图像中的干扰信息,有效实现了室内复杂环境下对地标线的高精度检测.通过在自采集的实际车间场景视频序列上进行大量对比实验,实验结果表明,本文方法在自采集的多组实际车间场景视频序列上测试的平均准确率、假阳性率和假阴性率分别达到了95.15%、3.73%和4.85%,平均每秒检测帧数为26fps,能够满足实际生产中对地标线检测的准确性和实时性要求.

一种改进ROI模型的舌体红外信息研究

舌诊是中医望诊的重要手段,同时,温度与人体的健康息息相关。为了研究舌面的脏腑功能定位及舌象温度关系的反映,论文提出了一种红外技术的感兴趣区域(region of interest, ROI)模型研究方法。首先,利用葛立恒扫描法和Bezier曲线对多边形ROI模型进行改进;然后,借助U-Net分割网络将提取出的温度信息进行训练与学习,从而做到批量处理舌体温度信息;最后,利用HSV色彩模型进行3D可视化,达成舌象温度分区的可视化研究。此外,为了验证该方法的准确性,实验还对模型截取出的舌体进行了评价指标验证,准确度可以达到0.991 1,分割效果极佳。研究表明:改进后的红外信息提取技术既能直观地观察到舌体的分区状况,也可以完整保留舌体的信息变化,为中医的数据化提供了完整可行性方案。实现了舌体红外信息数据的提取与中医诊断技术的有机结合。解决了中医一体化望诊的舌体信息完整性及准确性问题。

颈前路减压融合ROI-C^(TM)自锁系统治疗退行性颈椎病的Meta分析

目的:颈前路减压融合术是治疗退行性颈椎病的经典手术方式,钉板的使用增加了融合率及稳定性的同时,间接导致了邻近椎体退变和术后吞咽困难的发生。文章通过Meta分析方法比较ROI-C^(TM)自锁系统和传统融合器联合钉板内固定治疗退行性颈椎病患者的临床结果和并发症情况,为颈前路减压融合术中内固定方式的选择提供循证学支持。方法:检索中国知网、万方、维普、PubMed、Cochrane Library、Web of Science和Embase数据库,检索关于颈前路减压融合术中应用ROI-C^(TM)自锁系统与融合器联合钉板内固定治疗退行性颈椎病的中英文文献。检索时间范围为各数据库建库至2023年7月。由2名研究者严格按照纳入与排除标准选择文献,采用Cochrane偏倚风险工具对随机对照试验进行质量评价,NOS量表对队列研究进行质量评价。采用RevMan 5.4软件进行Meta分析。结局指标包括手术时间、术中出血量、日本骨科协会(Japanese Orthopaedic Association Scores,JOA)评分、颈椎功能障碍指数、C_(2)-C_(7)Cobb角、融合率、邻近椎体退变发生率、融合器沉降率和吞咽困难发生率。结果:共纳入13项研究,其中回顾性队列研究11项,随机对照试验2项,共1136例患者,ROI-C组569例,融合器联合钉板组567例。Meta分析结果显示:ROI-C组与融合器联合钉板组在手术时间(MD=-15.52,95%CI:-18.62至-12.42,P<0.00001),术中出血量(MD=-24.53,95%CI:-32.46至-16.61,P<0.00001),术后邻近节段退变率(RR=0.40,95%CI:0.27-0.60,P<0.00001)和术后总吞咽困难发生率(RR=0.18,95%CI:0.13-0.26,P<0.00001)均具有显著性差异。两者在术后JOA评分、颈椎功能障碍指数、C_(2)-C_(7)Cobb角、融合率和融合器沉降率方面无显著性差异(P≥0.05)。结论:在颈椎前路减压融合术中应用ROI-C^(TM)自锁系统与传统融合器联合钉板内固定治疗退行性颈椎病均可达到满意的临床效果,ROI-C^(TM)自锁系统操作更加简单,相比融合器联合钉板内固定能明显减少手术时间及术中出血量,在减少术后吞咽困难及邻近节段退变发生率等方面具有明显优势,对于跳跃型颈椎病及邻椎病翻修患者,更加推荐使用ROI-C^(TM)自锁系统。但鉴于其可能存在较高的沉降率,对于多节段且合并融合器沉降高危因素如骨质疏松、椎体终板破损的退行性颈椎病患者,仍建议使用融合器联合钉板内固定。

基于ROI边缘图像直线特征的井下带式输送机跑偏故障检测方法

针对井下带式输送机跑偏故障,传统故障检测容易受到噪点干扰,导致故障检测结果与实际不符的问题,提出结合ROI边缘图像直线特征对井下带式输送机跑偏进行故障检测,利用ROI方法锁定目标图像边缘,构建边缘检测器,设计图像边缘搜索路径,获取图像边缘信息。围绕某一特定区域进行模板匹配,采用外接正方形作为最优外接点,根据定位接点像素,按照空间递增顺序进行排序形成点集,避免噪点干扰。试验结果表明,根据ROI边缘图像直线特征变换原理,通过对点线对称,计算特征直线任意一点与原点距离,实现了从图像到参量空间的映射。同时,根据MT-CNN方法实现多层协同检测,结合ROI边缘图像直线坐标之间约束关系,实现了输送机跑偏故障检测。该方法图像灰度图谱与实际图谱一致,检测结果与实际数值误差最大值为50 mm,具有精准检测结果,可为井下带式输送机跑偏故障检测提供决策依据。

基于ROI理论的B站自媒体软广告研究——以UP主LKDY为例

随着移动互联时代的到来,自媒体已经成为一个重要的信息来源。在这一背景下,视频自媒体软广告应运而生并迅速发展壮大。本文基于ROI广告理论,结合B站UP主LKDY的案例,论述了视频自媒体软广告存在的主要问题,如产品广告与节目观众的关联度不够、节目内容陈旧传播效果不佳、广告情节设计平淡缺乏冲击力等,并针对上述问题探讨了相应的对策,旨在为自媒体软广告的优化提供参考。

Functional connectivity of paired default mode network subregions in patients with eye trauma

AIM:To study functional brain abnormalities in patients with eye trauma(ET)and to discuss the pathophysiological mechanisms of ET.METHODS:Totally 31 ET patients and 31 healthy controls(HCs)were recruited.The age,gender,and educational background characteristics of the two groups were similar.After functional magnetic resonance imaging(fMRI)scanning,the subjects’spontaneous brain activity was evaluated with the functional connectivity(FC)method.Receiver operating characteristic(ROC)curve analysis was used to classify the data.Pearson’s correlation analysis was used to explore the relationship between FC values in specific brain regions and clinical behaviors in patients with ET.RESULTS:Significantly increased FC between several regions was identified including the medial prefrontal cortex(MPFC)and left hippocampus formations(HF),the MPFC and left inferior parietal lobule(IPL),the left IPL and left medial temporal lobe(MTL),the left IPL and right MTL,and the right IPL and left MTL.No decreased region-to-region connectivity was detected in default mode network(DMN)sub-regions in patients with ET.Compared with HCs,ET patients exhibited significantly increased FC between several paired DMN regions,as follows:posterior cingulate cortex(PCC)and right HF(HF.R,t=2.196,P=0.032),right inferior parietal cortices(IPC.R)and left MTL(MTL.L,t=2.243,P=0.029),and right MTL(MTL.R)and HF.R(t=2.236,P=0.029).CONCLUSION:FC values in multiple brain regions of ET patients are abnormal,suggesting that these brain regions in ET patients may be dysfunctional,which may help to reveal the pathophysiological mechanisms of ET.

Artificial ground freezing of underground mines in cold regions using thermosyphons with air insulation

Current practice of underground artificial ground freezing(AGF)typically involves huge refrigeration systems of large economic and environmental costs.In this study,a novel AGF technique is proposed deploying available cold wind in cold regions.This is achieved by a static heat transfer device called thermosyphon equipped with an air insulation layer.A refrigeration unit can be optionally integrated to meet additional cooling requirements.The introduction of air insulation isolates the thermosyphon from ground zones where freezing is not needed,resulting in:(1)steering the cooling resources(cold wind or refrigeration)towards zones of interest;and(2)minimizing refrigeration load.This design is demonstrated using well-validated mathematical models from our previous work based on two-phase enthalpy method of the ground coupled with a thermal resistance network for the thermosyphon.Two Canadian mines are considered:the Cigar Lake Mine and the Giant Mine.The results show that our proposed design can speed the freezing time by 30%at the Giant Mine and by two months at the Cigar Lake Mine.Further,a cooling load of 2.4 GWh can be saved at the Cigar Lake Mine.Overall,this study provides mining practitioners with sustainable solutions of underground AGF.

戴明回归和ROI细化的机械仪表读数技术

针对目前机械仪表在读数时存在的辨识准确度不高、读数速度较慢等难题,本文提出一种以戴明回归与目标区精化为基础的读数方法。利用图象的帧间差异去除指针的摆动。在此基础上,采用区域细分算法,对待辨识仪器的各项指标进行精化。然后利用戴明回归方法进行拟合,得到仪器指示的拟合公式及倾斜度。通过实验来验证该方法的有效性和抗抖性。实验结果显示,本项目提出的新方法单幅影像的平均运算时间缩短189.363秒,并具备抗抖性能。

A phylogenetic approach identifies patterns of beta diversity and floristic subregions of the Qinghai-Tibet Plateau

Patterns of taxonomic and phylogenetic beta diversity and their relationships with environmental correlates can help reveal the origin and evolutionary history of regional biota.The Qinghai-Tibet Plateau(QTP)harbors an exceptionally diverse flora,however,a phylogenetic perspective has rarely been used to investigate its beta diversity and floristic regions.In this study,we used a phylogenetic approach to identify patterns of beta diversity and quantitatively delimit floristic regions on the Qinghai-Tibet Plateau.We also examined the relationships between multifaceted beta diversity,geographical distance,and climatic difference,and evaluated the relative importance of various factors(i.e.,climate,topography and history)in shaping patterns of beta diversity.Sørensen dissimilarity indices indicated that patterns of species turnover among sites dominated the QTP.We also found that patterns of both taxonomic and phylogenetic beta diversity were significantly related to geographical distance and climatic difference.The environmental factors that contributed most to these patterns of beta diversity include annual precipitation,mean annual temperature,climatic gradients and climatic instability.Hierarchical dendrograms of dissimilarity and non-metric multidimensional scaling ordination based on phylogenetic beta diversity data identified ten floristic subregions in the QTP.Our results suggest that the contemporary environment and historical climate changes have filtered species composition among sites and eventually determined beta diversity patterns of plants in the QTP.

Factors affecting land dissection density in geomorphological regions of China

Land dissection density(LDD)provides morphological evidence regarding prior intense soil erosion and quantifies the distribution of land dissections.A comprehensive understanding of the potential factors influencing the spatial pattern and value of the LDD is vital in geological disasters,soil erosion,and other related domains.Land dissection phenomena in China affects large areas with different morphological,pedological,and climatic characteristics.Prior studies have focused on the potential factors influencing the LDD at a watershed scale.However,these results are insufficient to reflect the status quo of dissection development and its primary influencing factors on a national scale.LDD’s spatial patterns and the dominant factors at a regional scale in millions of square kilometers remain to be ascertained.This study used the geomorphon-based method and the geographical detector model to quantify the spatial pattern of LDD over China and identify the dominant factors affecting this pattern in China’s six first-order geomorphological regions(GR1~GR6).The results yield the following findings:(1)LDD in China ranges from 0~4.55 km/km^(2),which is larger in central and eastern regions than in other regions of China;(2)dominant factors and their dominant risk subcategories vary with each geomorphological region’s primary internal and external forces;(3)the influence of natural factors is more significant on the large regional scale in millions of square kilometers compared to anthropogenic factors;relief degree of land surface(RDLS)is dominant in GR1,GR2,and GR5;the slope is dominant in GR6,soil type is dominant in GR3 and GR4,and lithology plays a critical role in the dominant interactions of GR3,GR4,and GR6;(4)the interactions between factors on LDD’s spatial pattern have a more significant effect than individual factors.

Research on the Digital Economy's Impact on China's Economic Growth:Based on the Variations in Urbanization Levels Across China's Eastern,Central,and Western Regions and Sectoral Heterogeneity

This paper uses inter-provincial panel data from 2011 to 2017,a linear regression model,and a threshold model to conduct empirical analyses of the impact of the digital economy on China's overall economic growth and the three main sectors of industry.The paper then investigates the impact and effects the digital economy has had on the economic growth of the three main sectors of industry in China's eastern,central,and western regions.Finally,the paper investigates the most significant differences among the various regions and the threshold effects of urbanization levels on the relationship between the digital economy and economic growth.The findings indicate a significantly positive correlation between the digital economy and regional economic growth.Moreover,geographical factors notably influence this correlation.The digital economy exerts a positive effect on all sectors of industry.It may not substantially impact industrial development in regions with highly developed infrastructure.Regarding the other regions,the digital economy exhibits varying degrees of impact due to the differences in the specific indicators.The conclusion drawn by the threshold model is that the magnitude of the threshold effect correlates with geographic factors.No threshold effect was observed in the eastern region,while the threshold effect occurred in the central region when the urbanization levels for the provinces were below 0.6645.Similarly,the threshold effect was noted in the western region when the urbanization level was below 0.3931.Considering all of this,the study also offers policy recommendations that will help balance the regional development of digital economies,accelerate the digital transformation of traditional industries,enhance digital infrastructure construction,refine the formulation and implementation of data policy,and establish relevant incentive mechanisms.

Strategies and Economic Benefit Analysis for Productive Landscape of Rape Flower Sea in Cold Regions

The cold regions are located in high latitudes and cold climates.The local excellent ornamental plant resources are relatively scarce.The plant species that are suitable for both ornamental and productive benefits of landscape of flower sea construction are also even fewer.Therefore,it is imperative to introduce and screen the plant resources suitable for cold regions to create the landscape of flower sea.The rape,an oilseed crop,was used as a research object in order to create a productive flower landscape with both ornamental and economic values in cold regions.Four rape flower varieties,Qingza No.5,7,9,and 11,were introduced from Qinghai Hufeng Agricultural Science and Technology Group Co.,Ltd.They were planted in the experimental practice base of Northeast Agricultural University in three batches.Development characteristics and seed yield of rape flowers on different sowing dates were studied.The fuzzy probability method was used to comprehensively evaluate the varieties.The results showed that the rape flowers grew well in Harbin City during the experimental sowing period,which could form a good landscape of flower sea and had a considerable rapeseed yield.It could be widely used in cold urban and rural areas,such as Harbin City.In view of the experimental results,the strategies of creating a productive landscape of rape flower sea were proposed and the economic benefits were analyzed.It could change the status quo of a uniform landscape of flower sea in cold regions,help the development of rural tourism,and promote local economic income.

An Assessment of Saltwater Intrusion in Coastal Regions of Lagos, Nigeria

This paper explains various factors that contribute to saltwater intrusion, including overexploitation of freshwater resources and climate change as well as the different techniques essential for effective saltwater intrusion management. The impact of saltwater intrusion along coastal regions and its impact on the environment, hydrogeology and groundwater contamination. It suggests potential solutions to mitigate the impact of saltwater intrusion, including effective water management and techniques for managing SWI. The application of A.I (assessment index) serves as a guideline to correctly identify wells with SWI ranging from no intrusion, slight intrusion and strong intrusion. The challenges of saltwater intrusion in Lagos and the salinization of wells were investigated using the hydro-chemical parameters. The study identifies four wells (“AA”, “CMS”, “OBA” and “VIL”) as having high electric conductivities, indicating saline water intrusion, while other wells (“EBM”, “IKJ, and “IKO”) with lower electric conductivities, indicate little or no salt-water intrusion, and “AJ” well shows slight intrusion. The elevation of the wells also played a vital role in the SWI across coastal regions of Lagos. The study recommends continuous monitoring of coastal wells to help sustain and reduce saline intrusion. The findings of the study are important for policymakers, researchers, and practitioners who are interested in addressing the challenges of saltwater intrusion along coastal regions. We assessed the SWI across the eight (8) wells using the Assessment Index to identify wells with SWI. Wells in “CMS” and “VIL” has strong intrusions. A proposed classification system based on specific ion ratios categorizes water quality from good (+) to highly (-) contaminated (refer to Table 4). These findings underscore the need for attention and effective management strategies to address groundwater unsuitability for various purposes.

Innovative Technologies for Large-Scale Water Production in Arid Regions: Strategies for Sustainable Development

Water scarcity in arid regions poses significant challenges to sustainable development and human well-being. This article explores both existing and innovative technologies and methods to produce large amounts of water to address these challenges effectively. Key approaches include atmospheric water generation, advanced desalination techniques, innovative water collection methods such as fog nets and dew harvesting, geothermal water extraction, and water recycling and reuse. Each method is evaluated for its feasibility with existing technology, potential time of implementation, required investments, and specific challenges. By leveraging these technologies and combining them into a multifaceted water management strategy, it is possible to enhance water security, support agricultural and industrial activities, and improve living conditions in arid regions. Collaborative efforts between governments, private sector entities, and research institutions are crucial to advancing these technologies and ensuring their sustainable implementation. The article provides a comprehensive overview of the current state of these technologies, their potential for large-scale application, and recommendations for future research and development.

Spatio-temporal variation of depth to groundwater level and its driving factors in arid and semi-arid regions of India

Climate change and increasing anthropogenic activities,such as over-exploitation of groundwater,are exerting unavoidable stress on groundwater resources.This study investigated the spatio-temporal variation of depth to groundwater level(DGWL)and the impacts of climatic(precipitation,maximum temperature,and minimum temperature)and anthropogenic(gross district product(GDP),population,and net irrigated area(NIA))variables on DGWL during 1994-2020.The study considered DGWL in 113 observation wells and piezometers located in arid western plains(Barmer and Jodhpur districts)and semi-arid eastern plains(Jaipur,Ajmer,Dausa,and Tonk districts)of Rajasthan State,India.Statistical methods were employed to examine the annual and seasonal patterns of DGWL,and the generalized additive model(GAM)was used to determine the impacts of climatic and anthropogenic variables on DGWL.During 1994-2020,except for Barmer District,where the mean annual DGWL was almost constant(around 26.50 m),all other districts exhibited increase in DGWL,with Ajmer District experiencing the most increase.The results also revealed that 36 observation wells and piezometers showed a statistically significant annual increasing trend in DGWL and 34 observation wells and piezometers exhibited a statistically significant decreasing trend in DGWL.Similarly,32 observation wells and piezometers showed an statistically significant increasing trend and 37 observation wells and piezometers showed a statistically significant decreasing trend in winter;33 observation wells and piezometers indicated a statistically significant increasing trend and 34 had a statistically significant decreasing trend in post-monsoon;35 observation wells and piezometers exhibited a statistically significant increasing trend and 32 observation wells and piezometers showed a statistically significant decreasing trend in pre-monsoon;and 36 observation wells and piezometers reflected a statistically significant increasing trend and 30 observation wells and piezometers reflected a statistically significant decreasing trend in monsoon.Interestingly,most of the observation wells and piezometers with increasing trends of DGWL were located in Dausa and Jaipur districts.Furthermore,the GAM analysis revealed that climatic variables,such as precipitation,significantly affected DGWL in Barmer District,and DGWL in all other districts was influenced by anthropogenic variables,including GDP,NIA,and population.As a result,stringent regulations should be implemented to curb excessive groundwater extraction,manage agricultural water demand,initiate proactive aquifer recharge programs,and strengthen sustainable management in these water-scarce regions.

Circulating metabolites difference in type 2 diabetes patients from regions:a cross-sectional study

Background:Type 2 diabetes(T2D)has already become a global pandemic.As its simple,rapid,economical,and relatively non-invasive,metabolic markers have become a method for T2D diagnosis.However,region,race,and diet all affect the metabolism of the body.The purpose of current study is to explore the differences of metabolites in T2D patients from regions.Methods:We recruited 103 T2D patients in two clinical centers,including 52 T2D patients from Beijing(T2D_(B))and 51 T2D patients from Kaifeng(T2D_(K)).The serum samples from T2D patients were analyzed using high-resolution mass spectrometer.After screened using univariate and multivariate analysis,the differential metabolites were identified.Moreover,to reveal biological information,we performed pathway analysis with the differential metabolites.Results:Thirty-six differential metabolites were identified,including 16 metabolites were higher concentrations while 20 metabolites were lower concentrations in the serum of T2D_(B) patients than T2D_(K) patients.There were higher serum concentrations of L-phenylalanine,4-methyl-2-oxovaleric acid,L-carnitine,decanoylcarnitine,9-decenoylcarnitine and sphinganine in T2D_(B) patients,in which decanoylcarnitine in T2D_(B) patients was up to 35-fold higher than T2D_(K) patients.While there were lower concentrations of L-valine,L-isoleucine,arachidonic acid,oleic acid,16-hydroxyhexadecanoic acid,lysophosphatidylcholine(18:0)and 1-Phenylethylamine in T2D_(B) patients,in which 1-phenylethylamine in T2D_(B) patients was decreased to 0.45-fold lower than T2D_(K) patients.The reason for the differences might be that phosphatidylethanolamine biosynthesis,phosphatidylcholine biosynthesis,valine,leucine and isoleucine degradation,and beta-oxidation of very long chain fatty acids were different in T2D_(B) patients and in T2D_(K) patients.Conclusion:Metabolites from different pathways are independently related to regions,providing valuable insight and potential for the diagnosis and treatment of T2D.

ROI-C零切迹融合器与传统钛板在双节段颈椎前路减压融合术中的应用

目的针对双节段颈椎前路减压融合术(ACDF)术中应用ROI-C零切迹融合器与传统Cage+钛板内固定的临床效果进行比较。方法以2018年1月~2021年1月河南省人民医院脊柱脊髓外科收治的65例连续双节段脊髓型颈椎病患者作为研究对象,均予以双节段ACDF手术,根据术中内植物分为两组:ROI-C组31例,术中植入ROI-C零切迹融合器;Cage+钛板组34例,术中均植入Cage+前路钛板固定。术后随访2年以上,对两组患者各项指标进行分组比较。结果与Cage+钛板组相比,ROI-C组患者的手术时间显著缩短(P<0.05),且ROI-C组患者的术中出血量显著减少(P<0.05)。ROI-C组术后出现吞咽困难2例(6.45%),均为轻度;Cage+钛板组出现8例(23.53%),其中轻度6例、中度2例,术后吞咽困难发生率有显著性差异(P<0.05)。与术前相比,两组患者术后3个月和末次随访的JOA评分和NDI指数均得到显著改善(P<0.05),但组间差异不显著(P>0.05)。末次随访时,按照Odoms标准:ROI-C组优19例、良12例,Cage+钛板组优20例、良14例,组间差异不显著(P>0.05)。与术前相比,两组患者术后3个月、末次随访时的C_(2-7) Cobb角和节段前凸角均获得了显著的矫正(P<0.05),但组间差异不显著(P>0.05)。截止末次随访,两组均获得植骨融合,融合率均为100%;ROI-C组未见嵌片松脱和融合器明显位移等现象,Cage+钛板组未见钛板松脱、断裂等现象。结论连续双节段脊髓型颈椎病ACDF应用ROI-C融合器和Cage+钛板均可获得满意的手术疗效。应用ROI-C融合器可缩短手术时间、减少术中出血量,并降低术后吞咽困难的发生率。

基于径向多项式密度Tesseroid体的大尺度重力场快速正演计算

在大尺度重力模拟中,为了考虑地球曲率的影响,通常将质量体沿经度、纬度及径向方向剖分为多个Tesseroid体,然后根据叠加原理将所有Tesseroid体重力效应之和近似为质量体的总重力场.在现有大多数方法中,总重力场的计算一般通过将各Tesseroid体的重力效应直接累加获得,尽管这种做法十分简单,但对于大尺度的复杂密度模型,其计算量十分巨大.为此,本文充分利用重力位、重力加速度及重力梯度张量核函数积分在经度方向的卷积特性,提出一种基于快速离散卷积算法和优化重力公式的高精度大尺度重力场模拟方法.该方法采用具有径向任意阶多项式密度的Tesseroid体来描述复杂密度分布,并以变密度Grombein优化公式为基础进行重力场正演模拟,从而有效克服经典球坐标系重力公式引起的极轴观测点奇异问题;同时联合Gauss-Legendre求积(GLQ)和水平方向的自适应网格剖分,实现重力积分的高精度计算,最后结合快速离散卷积算法获得质量体的重力效应.本文方法的加速策略通过如下途径实现:①假定经度方向的Tesseroid体具有相同尺寸,观测点位于同一高度且其采样间隔与Tesseroid体尺寸相等,由此建立与重力积分核对应的Toeplitz权系数矩阵,并利用Toeplitz对角线元素相等的特性,计算其第一列和第一行元素来复原完整矩阵,以此大大降低计算内存及计算时间;②利用基于FFT的离散卷积算法实现权系数矩阵与密度矩阵乘积的快速计算,从而进一步提高计算效率.数值算例表明,本文方法可实现近地表至卫星高度重力位、重力加速度及重力梯度张量的高精度计算,且其计算效率相较于直接累加法高出约3~4个数量级.该方法在WINTERC-G全球模型重力效应计算中的应用进一步证实了算法的可靠性和灵活性.本文快速算法是经典3D-GLQ方法的重要补充,对研究大尺度重力正反演问题、地形效应及地球内部结构等有重要意义.

Drugs used for pain management in gastrointestinal surgery and their implications

Pain is the predominant symptom troubling patients.Pain management is one of the most important aspects in the management of surgical patients leading to early recovery from surgical procedures or in patients with chronic diseases or malignancy.Various groups of drugs are used for dealing with this;however,they have their own implications in the form of adverse effects and dependence.In this article,we review the concerns of different pain-relieving medicines used postoperatively in gastrointestinal surgery and for malignant and chronic diseases.