期刊文献+
共找到2,101篇文章
< 1 2 106 >
每页显示 20 50 100
A morphological and anatomical study for tracking the growth and development of individual flowers and pods in soybean(Glycine max L.)
1
作者 Fang Li Yi-Ping Shao +4 位作者 Irsa Ejaz Zhen-Yuan Chen Zhi-Wei Wang Xin Wang Shun-Li Zhou 《The Crop Journal》 2025年第1期304-309,共6页
A morphology-based growth stage system should describe the growth and development of a crop and thereby help farmers and agronomists in formulating reasonable managementmeasures conducive to the development of marketa... A morphology-based growth stage system should describe the growth and development of a crop and thereby help farmers and agronomists in formulating reasonable managementmeasures conducive to the development of marketable products.However,existing growth stage systems for soybean are either based on plant growth or covered particular phases of flower or pod development,making it difficult to use for tracking the entire growth period of individual flowers and pods.Therefore,the first flower and pod,located at the base of the primary raceme in the eighth trifoliate node of the main stem,were chosen to illustrate growth dynamics during the full reproductive period.The size and fresh weight of the primary raceme in the eighth trifoliate leaf axil,the first flower and pod,the pistils in the first flower,and seeds in the first pod were examined,and the growth of these organs was depicted.Integrating the morphological characteristics and growth features of flowers and pods,as well as existing growth stage systems,the growth and development were delineated in 13 stages.In detail,we classified the flower phase based on the relative positions of floral components,inspired by the ratio of bract to flower used for staging,refined the lag phase proposed previously,retained the use of pod length to define the early pod phase,and innovatively described the late pod phase by the seed appearance.The developmental events in each stage of flower and pod were distinctive and closely connected to the corresponding morphology.Taken together,a more detailed growth stage system for describing individual flowers and pods in soybean was established.This system will serve as a valuable research tool for describing the development,gene expression,and cellular metabolism associated with the formation of flowers,pods,and seeds. 展开更多
关键词 SOYBEAN Growth stage system Flower and pod Morphology ANATOMY Growth and development
在线阅读 下载PDF
Pods Filling in Natural Pollination of 10 Spontaneous Cocoa Trees from French Guiana
2
作者 Inago Caudou Trebissou Gnion Mathias Tahi Kacou Antoine Alban M’bo 《Agricultural Sciences》 2025年第1期193-205,共13页
The study focuses on the filling of pods from ten cacao clones originating from French Guiana in Côte d’Ivoire. Two reference clones (IFC5 and NA32) were used as controls. The parameters studied include the numb... The study focuses on the filling of pods from ten cacao clones originating from French Guiana in Côte d’Ivoire. Two reference clones (IFC5 and NA32) were used as controls. The parameters studied include the number of ovules per ovary, the average number of beans per pod, the fresh bean weight, and the pod index. The aim was to evaluate the genetic variability and agronomic performance of these clones under natural pollination conditions. The results show significant genetic variability between the clones for all traits studied. The IFC5 clone, known for its excellent pod filling, exhibited the highest apparent fertility (0.91), while the GU183/A clone had the lowest filling (0.47). Three types of distributions of the number of beans per pod were identified: a right-skewed unimodal distribution, characteristic of well-filled clones;a left-skewed unimodal distribution, associated with poorly filled clones;and an intermediate bimodal distribution. These differences could be related to pollination compatibility and the availability of compatible pollen. Regarding the fresh bean weight and pod index, the GU183/A clone stood out with the heaviest beans (3.27 g) but had a high pod index (49.58), indicating relatively low productivity. None of the Guyanese clones achieved the filling level of the IFC5 clone, although some surpassed the NA32 control. This study highlights the importance of apparent fertility and the number of beans per pod as essential criteria for cacao genetic improvement programs. The authors recommend extending research to a larger number of Guyanese clones and exploring complementary traits, such as the influence of pollination type and intergroup compatibility. 展开更多
关键词 Theobroma cacao PHYTOPHTHORA Pod Index Apparent Fertility
暂未订购
基于CocoaPods的iOS开发私有公共基础代码库建设 被引量:2
3
作者 陈剑峰 《电子质量》 2022年第9期74-77,共4页
私有公共基础代码库建设一般在大厂等大型团队中都会部署到战略规划列表中,在涉及到机密而又需要复用的代码模块等场景中就需要私有库派上用场了;在建设私有库之前,需要先搭建好内部Git服务器或使用第三方平台私有Git仓库,然后将私有库... 私有公共基础代码库建设一般在大厂等大型团队中都会部署到战略规划列表中,在涉及到机密而又需要复用的代码模块等场景中就需要私有库派上用场了;在建设私有库之前,需要先搭建好内部Git服务器或使用第三方平台私有Git仓库,然后将私有库部署进去;创建索引库用于对所有私有库的索引;创建Cocoa Pods项目并对项目进行配置,将私有库代码模块等相关内容放置Cocoa Pods项目内,将Cocoa Pods项目提交到Git仓库并提交版本信息到索引库内;在项目中通过Cocoa Pods引用私有库进行验证。 展开更多
关键词 私有公共基础代码库建设 Cocoa pods 索引库 Cocoa pods项目 私有库部署
在线阅读 下载PDF
Effects of ABA on Photosynthetic Characteristics of Pods and Yield of Brassica napus 被引量:4
4
作者 李俊 张春雷 +3 位作者 马霓 余利平 晁赢 李玲 《Agricultural Science & Technology》 CAS 2012年第4期760-762,903,共4页
[Objective] The aim was to evaluate the effects of different concentrations of ABA on photosynthetic characteristics of pods and yield of Brassica napus and analyze the relationships between ABA concentration and yiel... [Objective] The aim was to evaluate the effects of different concentrations of ABA on photosynthetic characteristics of pods and yield of Brassica napus and analyze the relationships between ABA concentration and yield components, to provide theoretical basis for cultivation of high-yield rapeseed. [Method] At the end of flowering stage, the rape plants were separately sprayed with 1, 2, 100 and 200μmol/L of ABA; photosynthetic parameters, water use efficiency (WUE), yield and yield components of the rape plants were investigated 0, 5, 10 and 15 d later, respectively. [Result] ABA treatment with different concentrations significantly changed pod photosynthetic parameters and yield components of rapeseed. Low concentra- tions of ABA could improve pod's net photosynthetic rate and yield components while high concentrations had the contrary effect. [Conclusion] Whether ABA func- tioned in inhibiting or promoting role might depend on the interaction between endogenous hormone levels and exogenous ABA concentration. Improvement of WUE would be the main reason for yield increasing. 展开更多
关键词 Brassica napus L POD Abscisic acid (ABA) Photosynthetic characteristics YIELD
在线阅读 下载PDF
Role of phenolics as antioxidants,biomolecule protectors and as anti-diabetic factors-Evaluation on bark and empty pods of Acacia auriculiformis 被引量:1
5
作者 Arumugam Sathya Perumal Siddhuraju 《Asian Pacific Journal of Tropical Medicine》 SCIE CAS 2012年第10期757-765,共9页
Objective:To search for an efficient and inexpensive source of phytoconstituents with antioxidant potential and health promoting traits from bark and empty pods of Acacia auriculiformis (A.auriculiformis).Methods:Sa... Objective:To search for an efficient and inexpensive source of phytoconstituents with antioxidant potential and health promoting traits from bark and empty pods of Acacia auriculiformis (A.auriculiformis).Methods:Samples of bark and empty pod extracts were analyzed for bioactives(phenolics,flavonoids and proanthocyanidins) and subjected to free radical scavenging activity on DPPH<sup>*</sup>,ABTS<sup>?</sup>,OH<sup>?</sup>,O<sub>2</sub><sup>*</sup>,and NO along with the determination of reducing power, iron chelating activity and peroxidation inhibition.Defensive action of extracts on biomolecules and cell membranes were evaluated by DNA nicking assay and haemolysis inhibition assay respectively,α-amylase andα-glucosidase inhibitory potentials were also determined. Results:All the bioactives analyzed were higher in bark(B) than empty pods(EP)[TPC:B (574.51±16.11);EP(96.80±3.45) mg GAE/g.TFC:B(94.71±7.65);EP(24(?)87±20.45) mg RE/g. Proanthocyanidins:B(2.81±0.31);EP(1.25±0.01) mg LE/100 g DM]except flavonoids.Both the extracts showed higher quenching capacity on DPPH and ABTS(DPPH:B(0.21±0.01);EP(1.51±0.17) g extract/g DPPH.ABTS:B(111 519.14±79 340.91);EP(80 232.55±32 894.12) mmol TE/g) with the FRAP of B(84 515.63±3 350.69) and EP(47 940.79±1 257.60) mmol Fe((?))/g.Iron chelation was not observed.In addition,they showed lower quenching activity on OH<sup>?</sup>(B(48.95±1.72);EP(34.94±1.62)%) and equivalent quenching on O<sub>2</sub><sup>?</sup>(B(53.47±3.92);EP(24.41±2.61)%),NO(B(49.04±5.04); EP(51.00±5.13)%),peroxidation inhibition(B(67.50±5.50);EP(55.l±2.3)%) and antihaemolytic potential(B(87.60±6.84)%) towards authentic antioxidant standards.Interestingly,Empty pod extracts are devoid of antihaemolytic activity.Both the extracts showed dose dependent DNA protection.Besides this,bark and empty pod extracts exhibited dual inhibiting potential againstα-amylase andα-glucosidase enzymes.Conclusions:On summarization,it insinuated that both bark and empty pods can be used for the preparation of antioxidant/nutraceutical supplements and in anti-diabetic formulations. 展开更多
关键词 Phenolics BARK EMPTY pods ACACIA auriculiformis Antioxidant activity TypeⅡdiabetes
暂未订购
PODS管道数据模型及其应用 被引量:6
6
作者 陈辉 张文广 +3 位作者 张学峰 李建辉 王传宝 文斌 《天然气与石油》 2008年第6期23-26,共4页
PODS(Pipeline open Database Standard)是长输管道数据模型的国际标准,介绍了PODS发展历史和现状、主要结构和内容,及其在广东大鹏液化天然气有限公司的管道地理信息系统中的应用,可供有关数字管道的研究和建设单位参考。
关键词 数字管道 数据模型 pods GIS
在线阅读 下载PDF
Morpho-structural Features and Structural Classification of Chromite Pods in the Tropoje-Has Ophiolite Massif, Albania
7
作者 Ibrahim MILUSHI Nezir MEKSHIQI 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2016年第S1期234-,共1页
Tropoje-Has ophiolitic massif of eastern Mirdita(Albania)ophiolitic belt,is a major source for metallurgical chromite ore in Albania.Massif consists of a thick mantle section of SSZ type,8-10 km thick and
关键词 Morpho-structural Features and Structural Classification of Chromite pods in the Tropoje-Has Ophiolite Massif Albania
在线阅读 下载PDF
Natural Solar Drying and Charcoal Production by Pyrolysis of Empty Shells of Cocoa Pods Using a Carbonisation Stove Fitted with a Chimney
8
作者 Siaka Touré Adjo Christelle Ogo Modibo Sidibé 《Journal of Energy and Power Engineering》 CAS 2023年第4期109-120,共12页
The world’s production of cocoa highly has grown since 1960.In West Africa,the production reached about 3,000,000 tons in 2012.More than 50%of the world’s production of cocoa comes nowadays from Côte d’Ivoire ... The world’s production of cocoa highly has grown since 1960.In West Africa,the production reached about 3,000,000 tons in 2012.More than 50%of the world’s production of cocoa comes nowadays from Côte d’Ivoire and Ghana and Côte d’Ivoire is the biggest producer.After harvesting,the empty shells,considered as non-useful wastes,are abandoned in the fields where they become a source of pollution.That yields millions of tons of biomass that can be converted into charcoal,instead of being sources of pollution.In the present work,the drying kinetics of the empty wet shells were studied.Then,charcoal production by pyrolysis of those empty shells of cocoa pods was performed,using a carbonisation stove fitted with a chimney.The study showed that the empty shells have a high moisture content.The different phases of the drying were observed.The study compared the drying rates and the diffusion coefficients of a small sample and a big sample.Two experiences of carbonisation of the empty shells were successfully carried out.For the first experiment,the pyrolysis temperatures were recorded and the charcoal mass efficiency calculated.For the second experiment,the temperatures were higher and the result was colored charcoals.The colorations disappeared after some hours. 展开更多
关键词 Shells of cocoa pods solar drying diffusion coefficient charcoal production carbonisation stove.
在线阅读 下载PDF
Mapping QTL affecting the vertical distribution and seed set of soybean [Glycine max(L.) Merr.] pods 被引量:1
9
作者 Shiping Liu Hong Xue +16 位作者 Kaixin Zhang Ping Wang Daiqun Su Wenbin Li Shichao Xu Jianan Zhang Zhongying Qi Yanlong Fang Xiyu Li Yue Wang Xiaocui Tian Jie Song Jiajing Wang Chang Yang Sitong Jiang Wen-Xia Li Hailong Ning 《The Crop Journal》 SCIE CAS CSCD 2019年第5期694-706,共13页
Number of pods per plant and number of seeds per pod are quantitative,multigenic traits and important components of yield in soybean[Glycine max(L.)Merr.].Pods are distributed unevenly in the upper,middle,and lower se... Number of pods per plant and number of seeds per pod are quantitative,multigenic traits and important components of yield in soybean[Glycine max(L.)Merr.].Pods are distributed unevenly in the upper,middle,and lower segments of the plant and this distribution is affected by sowing date(SD).A population of four-way recombinant inbred lines(FW-RIL),containing 160 F2:8 individuals,was generated from the cross(Kenfeng 14×Kenfeng 15)×(Heinong 48×Kenfeng 19).A linkage map consisting of 275 simple sequence repeat(SSR)markers was used to map quantitative trait loci(QTL)associated with the production of one,two,three,and four seeds per pod in the upper,middle,and lower segments of plants at two SDs,totaling 12 measurements per SD.A wide range of variation in the twelve characteristics was observed among the four parental lines and the FW-RIL population at the two SDs.The effect of SD2(May 17,2016)on pod number was stronger than that of SD1(May 7,2016)because the heritability of each trait in the SD1 experiment was generally greater than that of SD2.The study identified 76 QTL controlling pod number,with the phenotypic variation explained by each QTL ranging from 1.86%to 13.71%.The numbers of QTL controlling one,two,three,and four seeds per pod were 28,23,23,and 23,respectively.There were 30,28,and 28 QTL controlling the pod number in the upper,middle,and lower segments of the plant,respectively.Forty-five QTL were identified at SD1 and 38 QTL were identified at SD2.Seventeen QTL were associated with pod-number traits.The QTL qPNA1–3 was associated with the number of pods containing one seed in the middle segment of the plant at both SDs.Sixty-three QTL were published QTL(common areas existed when integrating on a map GmComposite2003 of Wm82 based on left and right markers).and 13 QTL related to pod number were newly discovered.These results provide a reference for breeders to improve soybean yield by combining advantageous alleles for these QTL.Future studies may reveal candidate genes for these QTL and identify causal alleles for markerassisted selection. 展开更多
关键词 SOYBEAN Pod number QTL SOWING DATE Vertical distribution
在线阅读 下载PDF
Calibration and experiment of the contact parameters for the discrete meta-simulation of peanut pods during harvest in saline soils
10
作者 Zengcun Chang Jialin Hou +5 位作者 Baiqiang Zuo Shiyang Yin Dongjie Li Yuanhao Wang Pengcheng Ji Dongwei Wang 《International Journal of Agricultural and Biological Engineering》 2025年第4期53-62,共10页
In this study,a simulation model of peanut pod particles during harvest in saline soil was tested to calibrate contact parameters.Discrete meta-fill models of peanut pods were generated by a 3D meter and EDEM software... In this study,a simulation model of peanut pod particles during harvest in saline soil was tested to calibrate contact parameters.Discrete meta-fill models of peanut pods were generated by a 3D meter and EDEM software.The range of values of contact parameters for peanut pods was measured by conducting collision and other tests using a homemade test rig.The parameters that affect the significance of the simulation process of stacking angle were screened by the Plackett-Burman experiment,the steepest ascent experiment,and the Box-Behnken experiment.An optimization test determined the optimal simulation model parameters:The peanut pods had a Poisson’s ratio of 0.386 and a shear modulus of 3.04 MPa.The coefficient of recovery for pods-pods collisions was 0.335,the coefficient of static friction was 0.854,and the coefficient of rolling friction was 0.346.The coefficient of recovery of collision between the pods-65Mn steel was 0.339,the coefficient of static friction was 0.589,and the coefficient of rolling friction was 0.159.The test results showed a relative error of 0.42%between the stacking angle bench and simulation tests.The results can provide data support for studying the discrete metamaterial characterization of peanut pods. 展开更多
关键词 peanut pods saline soil discrete element contact parameter stacking angle calibration and experiment
原文传递
Oyster mushroom fermented Vachellia erioloba pods as replacement for wheat bran in broiler diets:Physiology and meat physicochemical and nutritional quality
11
作者 Phethile E.Mabuza Makiwa S.Mthana M.N.Mthiyane 《Animal Nutrition》 2025年第2期155-165,共11页
High feed costs and compromised meat quality are among the major issues perturbing the global broiler industry.This study therefore investigated Vachellia erioloba pods-derived oyster mushroom spent substrate(OMSS)as ... High feed costs and compromised meat quality are among the major issues perturbing the global broiler industry.This study therefore investigated Vachellia erioloba pods-derived oyster mushroom spent substrate(OMSS)as a potential nutraceutical feed ingredient to replace wheat bran for enhancing meat quality in broilers.Four hundred male Ross 308 chicks at 14 d of age were randomly allocated to 40 pens and fed treatment diets(0%,1.25%,2.5%,5%and 10%OMSS)each with 8 replicates of 10 birds for 28 d(grower:d 15 to 28,and finisher:d 29 to 42)prior to slaughter on d 43.Whilst there were no effects of diet on overall body weight gain(BWG),feed conversion efficiency(FCE),mortality rate,carcass traits,meat physicochemical quality,and most haemato-biochemistry parameters(P>0.05),dietary OMSS increased chicken overall feed intake(FI)(linear:P=0.043),gizzard weights(linear:P=0.021),and breast meat ether extract(EE)(linear:P<0.001)as it tended to increase its ash(P=0.064)contents.Further,OMSS linearly increased chicken white blood cells(P=0.044),lymphocytes(P=0.002),platelets(P=0.009),monocytes(P=0.007),and lipase activity(P=0.015),and linearly decreased its eosinophils(P=0.007)and platelet distribution width(PDW;P=0.003).Moreover,OMSS increased breast meat myristic(linear:P=0.012),palmitic(quadratic:P=0.015),palmitoleic(linear:P=0.023),and oleic(linear:P=0.002)acids,and impacted its total monounsaturated fatty acids(MUFAs),with 1.25%and 5%inclusion levels inducing the lowest and highest responses,respectively(P=0.024).In contrast,it decreased meat stearic(linear:P=0.004),eicosenoic(linear:P=0.004)and eicosadienoic(linear:P=0.025)acid contents.However,OMSS did not affect meat’s vaccenic,linoleic,α-linolenic,eicosatrienoic,total saturated fatty acids(SFAs),polyunsaturated fatty acids(PUFAs),n-3 PUFAs,n-6 PUFAs,and n-6/n-3 PUFA ratios(P>0.05).In conclusion,dietary OMSS replacement of up to 10%wheat bran increased broiler meat fatness,ash,and MUFAs,as well as immune competence,lipase activity,gizzard weights and FI without altering other performance variables,carcass-visceral traits,haemato-biochemistry,and meat physicochemical quality. 展开更多
关键词 BROILER Vachellia erioloba pod Solid-state fermentation Meat quality Fatty acid Growth performance
原文传递
Polyhydroxybutyrate production from Paeonia ostii pods by alkaline pretreatment and enzymatic hydrolysis followed by microbial fermentation
12
作者 Junhua Wang Qingxin Zhou +4 位作者 Jiying Qiu Yanhao Zhang Xiangyan Chen Yifen Wang Leilei Chen 《Journal of Future Foods》 2025年第5期513-519,共7页
To further develop the tree peony(Paeonia ostii)industry,methods for reusing the peony pods were explored,which are only used as low-value firewood.in the study,pods were subjected to alkaline pretreatment to produce ... To further develop the tree peony(Paeonia ostii)industry,methods for reusing the peony pods were explored,which are only used as low-value firewood.in the study,pods were subjected to alkaline pretreatment to produce fermentable reducing sugar for polyhydroxybutyrate(PHb)production.Fourier transform infrared(Ftir)results and reducing sugar yields for samples subjected to alkaline pretreatment were better than those for untreated samples,and the reducing sugar yield increased by 27.15%.the degree of hydrolysis and reducing sugar yield were increased by optimizing enzymatic parameters.the produced reducing sugar had carbon and nitrogen content of 31.69%and 0.095%,respectively,and most carbon came from glucose and xylose.the reducing sugar was fermented using a recombinant Escherichia coli strain,and the product was confirmed to be PHb by Ftir and proton nuclear magnetic resonance(1H NMr)analyses.the PHb yield increased by 36.67%when the produced reducing sugar,instead of glucose,was used as the carbon source.Meanwhile,corn steep liquor increased PHb production more significantly than the other tested nitrogen sources.the results of the study can promote the further development of the tree peony industry for commercial biodegradable PHb production by providing economical biomass. 展开更多
关键词 Paeonia ostii pod POLYHYDROXYBUTYRATE Alkaline pretreatment Enzymatic hydrolysis Recombinant Escherichia coli
在线阅读 下载PDF
Residue determination ofβ-cyfluthrin and imidacloprid as mix formulation in/on chickpea(Cicer arietinum)pods and soil and its risk assessment
13
作者 Suchi Chawla Paresh G.Shah +3 位作者 Anil R.Patel Hemlatta K.Patel Kiran M.Vaghela Priti P.Solanki 《Food Quality and Safety》 SCIE 2018年第2期75-81,共7页
OBJECTIVES:A field experiment was conducted at Agricultural Research Station for irrigated crops at Thasara,Anand Agricultural University,Anand,to study the dissipation and risk assessment ofβ-cyfluthrin and imidaclo... OBJECTIVES:A field experiment was conducted at Agricultural Research Station for irrigated crops at Thasara,Anand Agricultural University,Anand,to study the dissipation and risk assessment ofβ-cyfluthrin and imidacloprid as combination product in/on chickpea.MATERIALS AND METHODS:Solomon 300 OD comprising 9 per centβ-cyfluthrin and 21 per cent imidacloprid was foliar sprayed at the doses of 18+42g a.i.ha−1(standard dose)and 36+84g a.i.ha−1(double dose).Totally three sprays were made at an interval of 1 week starting from fruiting stage.RESULTS AND DISCUSSIONS:The residues ofβ-cyfluthrin estimated using gas chromatograph with electron capture detector(GC-ECD)showed an initial deposit of 0.16 and 0.27μg g−1 in standard and double doses,respectively.The residues for corresponding doses persisted till 7th and 10th day after application and reached below determination level of 0.01μg g−1 on the 10th and 15th day,respectively.Imidacloprid was estimated using high performance liquid chromatography(HPLC)and showed initial deposits of 1.22 and 2.7μg g−1 in standard and double doses,respectively.Its levels reached below the determination level(0.01μg g−1)on the 15th day in green pods.Statistical analysis of dissipation kinetics showed thatβ-cyfluthrin followed zero-order kinetics in standard dose with half-life of 7.27 days.In double dose,the dissipation kinetics followed first-order kinetics with half-life of 9 days.Imidacloprid followed first-order kinetics in both the doses with half-life of 6.7 and 7.7 days.CONCLUSIONS:A pre-harvest interval(PHI)of 15 days is suggested.Theoretical risk assessment calculated as hazard quotient was less than 1,rendering the use of combination product as safe-provided proper PHI is followed. 展开更多
关键词 CHICKPEA β-cyfluthrin IMIDACLOPRID DISSIPATION dissipation kinetics RESIDUE risk assessment pods.
原文传递
基于POD方法的对转压气机叶顶非定常流场分析 被引量:1
14
作者 王磊 高丽敏 +2 位作者 茅晓晨 郭彦超 俞一波 《航空动力学报》 北大核心 2025年第2期46-60,共15页
为深入研究对转压气机内的非定常流动特征及其流动机理,基于非定常数值模拟和本征正交分解(POD)方法开展了对转压气机近失速工况下的叶顶非定常流场分析。结果表明:上游转子(R1)叶顶非定常流场的主导频率为1BPF(叶片通过频率),其主导结... 为深入研究对转压气机内的非定常流动特征及其流动机理,基于非定常数值模拟和本征正交分解(POD)方法开展了对转压气机近失速工况下的叶顶非定常流场分析。结果表明:上游转子(R1)叶顶非定常流场的主导频率为1BPF(叶片通过频率),其主导结构主要是由下游势流的影响以及相邻叶片叶尖泄漏流及二次泄漏流冲击作用导致的,并且下游转子(R2)的势流作用对转子R1的非定常流动影响较大;在转子R2叶顶流场中,POD方法成功捕捉到了叶片前缘进口通道处由泄漏流溢流所导致的主要流动结构,其主导频率为0.8BPF,并且在转子R2非定常流场中起主导作用。同样转子R2受到两排转子干涉的影响,模态的主导频率为1BPF。此外,通过POD模态进行叶顶流场重构进一步反映出了对非定常流场起主导作用的流动结构。 展开更多
关键词 对转压气机 本征正交分解(POD)方法 非定常流场 POD模态 近失速流场
原文传递
基于场量梯度的快照分区POD降阶计算方法 被引量:1
15
作者 杨帆 张潋镪 +2 位作者 何永胜 王鹏博 姜慧 《高电压技术》 北大核心 2025年第1期31-39,共9页
随着数字化电力系统的不断发展,对高价值电力装备数字孪生模型的研究成为热点。为满足计算的时效性,通常采用模型降阶的方法,其中本征正交分解法(proper orthogonal decomposition,POD)是最为常用的方法之一。传统的POD方法在构造快照... 随着数字化电力系统的不断发展,对高价值电力装备数字孪生模型的研究成为热点。为满足计算的时效性,通常采用模型降阶的方法,其中本征正交分解法(proper orthogonal decomposition,POD)是最为常用的方法之一。传统的POD方法在构造快照时无法高效提取网格节点信息,造成大的计算量、存储资源浪费。为此,该文提出基于场量梯度的快照分区POD降阶计算方法,以快照中各节点场量梯度为依据对计算域进行分区处理,通过对不同分区的节点数量进行不同程度的缩减,实现了高效的POD降阶计算。以换流变阀侧套管极性反转电场作为算例,对该文提出分区降阶方法的可行性及高效性进行了验证。研究结果显示:相较于有限元方法,计算时间缩短97.1%,同时相较于传统的POD方法,其快照中节点数量减少95.2%,节约存储资源91.7%。同时,分区降阶计算的准确率高,平均误差仅为0.80%,实现了对阀侧套管极性反转电场的高效计算。 展开更多
关键词 模型降阶方法 本征正交分解法 场量大梯度 POD快照 换流变 阀侧套管
原文传递
基于星载单频BDS-3的低轨卫星准实时精密定轨 被引量:1
16
作者 孙玉强 袁兴明 宋传峰 《导航定位学报》 北大核心 2025年第2期126-131,共6页
为了进一步提高基于国产低成本星载单频北斗三号全球定位导航系统(BDS-3)接收机的低轨卫星精密定轨精度,提出一种基于星载单频BDS-3的低轨卫星准实时精密定轨方法:分析星载BDS-3数据质量;然后采用半和改正模型实现高精度精密定轨。实验... 为了进一步提高基于国产低成本星载单频北斗三号全球定位导航系统(BDS-3)接收机的低轨卫星精密定轨精度,提出一种基于星载单频BDS-3的低轨卫星准实时精密定轨方法:分析星载BDS-3数据质量;然后采用半和改正模型实现高精度精密定轨。实验结果表明,星载BDS-3接收机能同时跟踪平均6.8颗卫星,超过93.26%的历元下能跟踪超过4颗卫星,星上接收机几何精度因子(GDOP)、位置精度因子(PDOP)及时间精度因子(TDOP)分别为6.2、5.3及3.0,单频伪距和载波相位观测观测噪声分别为0.13 m和0.01 m;采用武汉大学多模GNSS实验跟踪网(MGEX)分析中心发布的准实时精密轨道/钟差产品(NRT)可实现准实时精密定轨,伪距和载波相位验后残差均方根(RMS)值分别为9.57 m和86.34 mm,重叠弧段切向、径向、法向及三维方向位置精度分别为0.318、0.139、0.198 m及0.400 m,速度精度分别为0.197、0.156、0.369 mm/s及0.446 mm/s。相关成果可为搭载单频BDS-3低成本接收机的对地观测卫星计划提供参考。 展开更多
关键词 单频信号 北斗三号全球卫星导航系统(BDS-3) 低轨(LEO)卫星 准实时 精密定轨(POD)
在线阅读 下载PDF
基于改进型Gappy POD的亚跨声速压气机叶型反设计方法
17
作者 茅晓晨 陈飞 陈璇 《航空动力学报》 北大核心 2025年第10期424-436,共13页
针对基本Gappy POD(proper orthogonal decomposition)方法的反设计精度较低、可操作性不强,且对跨声速叶型的反设计精度低于亚声速叶型的问题提出改进策略,发展了一套完整的改进型Gappy POD方法。通过验证算例证明了基于改进型Gappy PO... 针对基本Gappy POD(proper orthogonal decomposition)方法的反设计精度较低、可操作性不强,且对跨声速叶型的反设计精度低于亚声速叶型的问题提出改进策略,发展了一套完整的改进型Gappy POD方法。通过验证算例证明了基于改进型Gappy POD方法的压气机叶型反设计更加简单高效,与基本Gappy POD方法相比,两种叶型的反设计精度分别提高了61%和78%,同时反设计耗时分别缩短了77%和63%。进一步研究发现改进型Gappy POD方法对叶型拟合精度提高的收益主要来自压力面重构精度的提高,而在吸力面后半段叶型几何偏差较大,且几何偏差呈现从前缘到尾缘先增大后减小的趋势。 展开更多
关键词 压气机叶型 反设计 本征正交分解(POD) Gappy POD 重构精度
原文传递
叶尖间隙及转速增大对对转压气机非定常流场的影响研究
18
作者 刘波 李敏 +1 位作者 张瑞辰 茅晓晨 《航空动力学报》 北大核心 2025年第10期387-402,共16页
以两级轴流对转压气机(CRAC)为对象,研究了叶尖间隙(TCS)耦合转速变化引起的流场非定常特性。在数值模拟结果的基础上,采用本征正交分解(POD)方法获取POD模态分布规律,进一步分析了近失速工况下叶尖间隙流场的流动特性。数值和FFT结果表... 以两级轴流对转压气机(CRAC)为对象,研究了叶尖间隙(TCS)耦合转速变化引起的流场非定常特性。在数值模拟结果的基础上,采用本征正交分解(POD)方法获取POD模态分布规律,进一步分析了近失速工况下叶尖间隙流场的流动特性。数值和FFT结果表明:随着叶尖间隙的增大,叶尖泄漏流(TLF)增强,叶尖泄漏涡(TLV)破碎加剧,引起的非定常波动范围增大,波动强度减弱;后排转子(R2)叶尖泄漏流波动频率提高;R2叶尖泄漏流溢出通道前缘并与相邻叶片前缘发生干涉是导致其前缘非定常性突增的原因。POD分析验证了上述的结论,并揭示了叶表静压波动区域产生的原因,还发现叶尖间隙增大导致前排转子(R1)的三维流场主导模态结构减小,R1高阶模态结构沿径向向叶根方向迁移。随着转速增大,上游转子对下游转子的干涉也随之增大。 展开更多
关键词 对转压气机 叶尖间隙 转速 叶尖泄漏流 非定常流动 POD方法
原文传递
Preventing IP Spoofing in Kubernetes Using eBPF
19
作者 Absar Hussain Abdul Aziz +1 位作者 Hassan Jamil Syed Shoaib Raza 《Computers, Materials & Continua》 2025年第8期3105-3124,共20页
Kubernetes has become the dominant container orchestration platform,withwidespread adoption across industries.However,its default pod-to-pod communicationmechanism introduces security vulnerabilities,particularly IP s... Kubernetes has become the dominant container orchestration platform,withwidespread adoption across industries.However,its default pod-to-pod communicationmechanism introduces security vulnerabilities,particularly IP spoofing attacks.Attackers can exploit this weakness to impersonate legitimate pods,enabling unauthorized access,lateral movement,and large-scale Distributed Denial of Service(DDoS)attacks.Existing security mechanisms such as network policies and intrusion detection systems introduce latency and performance overhead,making them less effective in dynamic Kubernetes environments.This research presents PodCA,an eBPF-based security framework designed to detect and prevent IP spoofing in real time while minimizing performance impact.PodCA integrates with Kubernetes’Container Network Interface(CNI)and uses eBPF to monitor and validate packet metadata at the kernel level.It maintains a container network mapping table that tracks pod IP assignments,validates packet legitimacy before forwarding,and ensures network integrity.If an attack is detected,PodCA automatically blocks spoofed packets and,in cases of repeated attempts,terminates compromised pods to prevent further exploitation.Experimental evaluation on an AWS Kubernetes cluster demonstrates that PodCA detects and prevents spoofed packets with 100%accuracy.Additionally,resource consumption analysis reveals minimal overhead,with a CPU increase of only 2–3%per node and memory usage rising by 40–60 MB.These results highlight the effectiveness of eBPF in securing Kubernetes environments with low overhead,making it a scalable and efficient security solution for containerized applications. 展开更多
关键词 CNCF eBPF pods SPOOFING IP DDOS container orchestration PACKETS EKS CNI CNM VM
在线阅读 下载PDF
TOPAZ-Ⅱ反应堆堆芯的稳态热工代理模型 被引量:1
20
作者 廖瑞安 王学松 +4 位作者 祁琳 张大林 田文喜 苏光辉 秋穗正 《核动力工程》 北大核心 2025年第3期24-33,共10页
TOPAZ-Ⅱ反应堆是前苏联设计的空间核反应堆电源,以钠钾合金(NaK-78)为冷却剂,采用热离子转换发电原理为负载提供电力。为了快速准确地计算出堆芯的稳态热工参数,建立了高精度的堆芯稳态热工代理模型。本文首先使用Fluent开展堆芯稳态... TOPAZ-Ⅱ反应堆是前苏联设计的空间核反应堆电源,以钠钾合金(NaK-78)为冷却剂,采用热离子转换发电原理为负载提供电力。为了快速准确地计算出堆芯的稳态热工参数,建立了高精度的堆芯稳态热工代理模型。本文首先使用Fluent开展堆芯稳态热工计算,选择中心纵截面网格节点温度为样本数据。然后使用本征正交分解(POD)方法提取样本数据中的主要特征,根据99.999%的能量占比保留前10阶模态完成模型降阶,最后基于反向传播(BP)神经网络建立堆芯的稳态热工代理模型,并将代理模型与Fluent进行对比验证,结果表明代理模型对网格节点温度的计算最大误差为9.95 K,相对误差小于1%,计算时间小于1 s。以冷却剂最热通道出口温度为参考,通过代理模型计算得到冷却剂保持单相工作状态的流量-功率百分值之比应大于0.35。因此,本文建立的稳态热工代理模型可以快速准确地计算得到堆芯的稳态热工参数,实现了对堆芯的仿真预测,并为堆芯热工安全分析提供了一定的参考。 展开更多
关键词 TOPAZ-Ⅱ反应堆 热工代理模型 本征正交分解(POD) 反向传播(BP)神经网络
原文传递
上一页 1 2 106 下一页 到第
使用帮助 返回顶部