mlsa-iai-msu-lab/ru_sci_bench_zho_cite_reranking huggingface dataset:
Residues of Organochlorine Pesticides(OCPs) in Agricultural Soils of Zhangzhou City,China

A soil survey was conducted in Zhangzhou City,an important agricultural region in south of the Fujian Province,China.93 surface soil samples were collected in the paddy fields,vegetable lands,orchards and tea plantations from Zhangzhou City.An additional soil profile was sampled in a paddy field as previous research had indicated high concentrations of organochlorine pesticides(OCPs) in the paddy fields.Dichlorodiphenyltrichloroethanes(DDTs) ranged from 0.64-78.07 ng g~(-1) dry weight and hexachlorocyclohexanes(HCHs) ranged from 0.72-30.16 ng g 1 dry weight in the surface soil of the whole study region.Ratios of α-HCH/γ-HCH < 4 and o,p-DDT/p,p-DDT > 1 in all soil samples suggested that lindane and dicofol were widely applied in this region in the past.Concentrations of HCHs and DDTs in soils from the four land use types followed the orders:paddy fields > vegetable lands > tea plantations > orchards and tea plantations > orchards > paddy fields > vegetable lands,respectively.Analyses of the data showed no correlation(r < 0.1) between elevation and OCPs contents in paddy fields,orchards and vegetable lands,indicated no significantly different features in distribution of HCHs and DDTs in the soils from low lying plains and mountains and the unsystematic usage of OCPs,and highlighted the fragmented nature of agricultural production in Zhangzhou,as well as the reemission of OCPs from the soils,where high OCPs concentrations were found,in Longhai of Zhangzhou.In addition,no obvious relationship between the OCPs and total organic carbon(TOC)(r < 0.3) was observed in the soil profile.The mean contribution of dicofol in total DDTs was 66% in the whole Zhangzhou region.The approximate burdens of HCHs and DDTs in the surface layer of 0-20 cm were 0.44 and 1.55 t,respectively.The storage of both HCHs and DDTs in soil surface layer(0-20 cm) accounts for 40% burden of the soil layer of 0-50 cm(1.10 t HCHs and 3.87 t DDTs),in which the highest concentrations of OCPs were observed in soil profile.
Enhancement of Superoxide Dismutase and Catalase Activities and Salt Tolerance of Euhalophyte Suaeda salsa L. by Mycorrhizal Fungus Glomus mosseae

Arbuscular mycorrhizal (AM)-mediated plant physiological activities could contribute to plant salt tolerance. However, the biochemical mechanism by which AM fungi enhance salt tolerance of halophytic plants is unclear. A pot experiment was conducted to determine whether salt tolerance of the C 3 halophyte Suaeda salsa was enhanced by the AM fungus Glomus mosseae. When 60-day-old S. salsa seedlings were subjected to 400 mmol L~(-1) NaCl stress for 35 days, plant height, number of leaves and branches, shoot and root biomass, and root length of G. mosseae-colonized seedlings were significantly greater than those of the nonmycorrizal seedlings. Leaf superoxide dismutase (SOD) activity at all sampling times (weekly for 35 days after salt stress was initiated) and leaf catalase (CAT) activity at 2 and 3 weeks after salt stress was initiated were also significantly enhanced in G. mosseae-colonized S. salsa seedlings, while the content of leaf malondialdehyde (MDA), a product of membrane lipid peroxidation, was significantly reduced, indicating an alleviation of oxidative damage. The corresponding leaf isoenzymes of SOD (Fe-SOD, Cu/Zn-SOD1, and Cu/Zn-SOD2) and CAT (CAT1 and CAT2) were also significantly increased in the mycorrhizal seedlings after 14 days of 400 mmol L-1 NaCl stress. Our results suggested that G. mosseae increased salt tolerance by increasing SOD and CAT activities and forming SOD and CAT isoforms in S. salsa seedlings.
Structural characterization of 1β,11α-dihydroxycanrenone biotrans-formed from canrenone by Aspergillus ochraceus SIT34205

Canrenone(1) was biotransformed into 11α-hydroxycanrenone(2) and a main byproduct(3) by Aspergillus ochraceus SIT34205.Compound 3 was separated and purified using silica gel column chromatography,and its structure was characterized via MS and NMR methods.These results indicated that 3 was 1β,11α-dihydroxycanrenone and the product of further hydroxylation of 2.Thus,investigating the structure and synthesis of 3 may be a promising method to improve the efficiency and purity of 2.
First example of multicomponent synthesis of 1-ethoxy-3-(4-aryl)-1-phenyl- 1H-benzo[f]-chromene derivatives

A new series of 1-ethoxy-3-(4-aryl)-1-phenyl-1H-benzo[f]chromenes have been synthesized efficiently.The procedure involves the multicomponent reaction of 2-naphthol,acetophenone derivatives,and triethyl orthobenzoate catalyzing by efficient bis(2-anilinotropone) Ti complex.
OIL/WATER SEPARATION IN A LIQUID-LIQUID CYLINDRICAL CYC-LONE

The oil/water separation in a liquid-liquid cylindrical cyclone is experimentally studied in this article.The effects of the flow split-ratio and the flow rate on the oil/water separation performance are determined.From the experimental results,it is shown that with the increase of the flow split-ratio,the oil/water separation efficiency is enhanced at first,and an optimal flow split-ratio exists,beyond that optimal split-ratio,the watercut in the underflow keeps constant,while the oil content in the overflow begins to decrease.The process of the oil core structure formation and the phase distribution in the cyclone are determined by numerical simulations.Furthermore,the dependence of the separation efficiency on the Reynolds number and the flow split-ratio is investigated based on a dimensional analysis.A comparison between the predicted values and the experimental data shows a good agreement.
高产、高蛋白黍子新品种“冀张黍1号”的选育

黍子新品种冀张黍1号是张家口市农科院以8012-16、涿鹿大红黍、蔚县柳心白和宣化小红黍4个品种(品系)为亲本,采用复合杂交的方法,单株系统选育而成的品种,2010年通过鉴定。该品种具有高产、高蛋白特性,一般产量4 000 kg/hm2左右,蛋白质含量高达15.74%。生育期96~102 d,全生育期需有效积温2 241.7~2 381.8℃,适宜冀北、雁北、内蒙等同类型黍子产区种植。
黄杜鹃(Rhododendron molle)种苗特性的研究

将黄杜鹃种苗置于大棚温室和户外环境观察其生长状况,结果发现:从10月份到第2年3月中旬,置于大棚温室的黄杜鹃能够完整无损的保留叶片,越过冬天;从3月中旬到9月底,将黄杜鹃置于室外,其生长迅速;年生长变化呈"快-慢-快-慢"的生长规律,一年四季植株上都有叶子,夏秋两季逐渐以新叶取代老叶;对其枝条进行形态解剖观察,结果表明,黄杜鹃的不定根原基起源于髓射线与维管形成层交叉的部位及髓薄壁组织,未发现愈伤组织分化成不定根。
混合盐碱胁迫对水稻种子萌发的影响

为探明混合盐碱胁迫对水稻(Oryza sativa L.)种子萌发的影响,采用纸上萌发法,用不同浓度的NaCl、Na2SO、NaHCO3和Na2CO3混合液对水稻种子进行萌发试验。结果表明:在混合盐碱胁迫下,水稻种子的发芽率、发芽势、发芽指数和活力指数均随盐浓度的升高和pH值增大呈下降趋势。低盐或低碱胁迫对水稻种子萌发影响较小,高盐或高碱胁迫下水稻种子萌发受到严重影响,水稻种子萌发主要受到盐浓度的影响,当盐浓度达200 mmol/L时,各盐组合水稻种子均不萌发。
淋洗液自动发生-离子色谱法测定饮用水中微量的2,4-滴

2,4-滴是目前国内外农业生产中广泛使用的除草剂及作物生长促进剂,低含量的2,4-滴作为生长激素促进植物生长、防止落花落果,高含量的2,4-滴作为除草剂在果蔬生产中使用较多。国家标准方法GB 5749-2006规定2,4-滴的限量标准为0.03mg.L-1。2,4-滴常见的检测方法有气相色谱法、高效液相色谱法、液相色谱-质谱法等。上述方法多数需样品前处理，有的还需要柱后衍生，操作繁琐费时，衍生条件较难控制，且有些衍生试剂对人体有害。液相色谱-质谱法省去了样品预处理和衍生的麻烦，但仪器昂贵，不利于普及。我国《生活饮用水卫生规范》相关方法使用重氮甲烷进行衍生方法灵敏度高，但是试剂毒性大反应条件苛刻不易重复。本工作以淋洗液自动发生-离子色谱法对饮用水中的2，4-滴进行测定，样品不需前处理，过0。25μm微孔滤膜后直接进样测定，在实际样品分析中得到较好的应用。
火焰原子发射光谱法测定卤水中锂

卤水是天然水中矿化度很高的水,也被称为液态矿。柴达木盆地具有非常丰富的盐湖资源,特别是锂资源,具有储量大、品位高、分布集中的特点,号称世界三大锂矿区之一。在利用盐湖锂资源开发制备锂盐的生产过程中,随着盐湖卤水的不断蒸发浓缩，其化学组分也在不断发生变化，对锂的测定造成较大的困难。
从参与2例儿科疾病诊治看临床药师在临床合理用药中的作用——第二届《中国药房》杂志“药学典型病案讨论学术会”会议纪要

上海新华医院这个病例在用药的合理、安全方面都是做得非常好的，有几个小问题：（1）你们和临床医师沟通的时间是定期的吗？（张春：我是每天去查房，医师一般在交班后8：30左右进病房查房，我不参加他们的交班，我一般会在8：10左右到病房，先把患者的报告和医嘱看一遍，如果发现问题以便及时和医师沟通）；（2）临床药师要协助选药、用药，那么你认为临床药师的临床功底是通过什么途径获得的呢？（张春：我本科是临床医学专业，研究生是药理学专业）我认为，临床药师应每天到病房参与查房，时间长了见的临床实例多了，对临床的用药习惯、药物作用和价值就会有一个适当的指导。
不远万里来到中国的“瓦良格”号

2011年"两会"期间,中国海军副司令员徐洪猛回应"瓦良格"号是否将于2011年部署的问题时说:"会有一个适当时间、适当地点、适当的人来宣布这个事,我无权宣布。"4月6日,环球网军事综合栏目以"巨舰即将出航圆70年中国人航母梦"为题,展示20页"瓦良格"号航母照片。6月初,解放军总参谋长陈炳德在访美回国前向媒体确认:"现在航母在建,还没建成,等建完再说。”这是中国军方最高层将领首度证实航母在建。中国第一艘航母将以苏联的“瓦良格”号改装而成,这已经是一个公开的秘密。中国实现航母从无到有飞跃的那一天,近在眼前。
不同施肥水平及玉米种植对土壤微生物生物量碳氮的影响

以裸地(不种植作物)和玉米种植的田间小区试验为平台,研究不同施肥水平及玉米种植对土壤微生物生物量碳氮的影响。结果表明,当不施肥时,土壤微生物生物量碳氮含量裸地平均值分别为175.98 mg/kg和26.04 mg/kg,种植玉米小区的平均值分别为161.65 mg/kg和22.70 mg/kg,土壤微生物生物量碳氮低于裸地;而施肥时,裸地的土壤微生物生物量碳氮平均值的变化范围分别为182.27~206.27 mg/kg和27.41~31.22 mg/kg,种植玉米小区的变化范围分别为194.70~235.58 mg/kg和35.76~44.66 mg/kg,土壤微生物生物量碳氮高于裸地,可见土壤碳氮的平衡对于土壤微生物生物量碳氮极为重要。裸地和玉米种植小区土壤微生物生物量碳氮均随着施肥量的增加呈现出先增加后降低的趋势,其施氮水平拐点分别为70 kg/hm~2和150kg/hm~2,表明施肥水平对土壤微生物生物量碳氮具有显著影响。另外,玉米各生育期间土壤微生物生物量碳氮也存在着显著差异,其中,土壤微生物生物量碳氮含量在拔节期处于最低,变动范围分别为154.46~229.09 mg/kg和18.84~31.44 mg/kg;抽雄期处于最高,变动范围分别为171.71~242.48 mg/kg和30.01~50.54 mg/kg。
4JFM150型秸秆粉碎灭茬机的研制与试验

研制开发了4JFM150型秸秆粉碎灭茬机,该机集秸秆粉碎与灭茬两种单一功能于一体。通过性能试验和生产试验实证表明,该机各项技术、性能指标达到设计要求,符合相关国家标准,其作业质量能够满足农艺要求。
经济转型期矿业城市自然系统脆弱性的评价与调控——以吉林省辽源市为例

辽源市是典型的以煤炭资源为主的矿业城市,经过长期的开采,其域内的煤炭资源已经趋于枯竭,目前正处于经济转型时期。运用熵权指数法对1990—2009年共20个样本年的辽源市自然系统脆弱性进行了评价,结果表明辽源市自然系统脆弱性的演化趋势经历了两个阶段:1990—2001年,辽源市自然系统脆弱性呈现震荡减弱的趋势;2002—2009年,辽源市自然系统脆弱性呈现震荡增强的趋势,并提出了降低脆弱性的调控策略。
用HPLC法测定盐酸法舒地尔注射液中盐酸法舒地尔的含量

盐酸法舒地尔(fasudil hydrochloride)是一种肌球蛋白轻链磷酸化酶、Rho-激酶抑制剂和细胞内钙离子拮抗剂,对脑血管有高度的选择性和很强的扩张作用,可改善和预防蛛网膜下腔出血后的脑血管痉挛及随之引起的脑缺血症状。本品的活性成分为法舒地尔,一般将其制成盐酸盐、马来酸盐、苯磺酸盐等。已有文献报道马来酸法舒地尔注射液中马来酸法舒地尔含量和有关物质的测定,以及血浆中法舒地尔的测定,关于盐酸法舒地尔注射液含量测定方法未见报道。作者建立了HPLC法测定盐酸法舒地尔注射液的含量,方法准确、简便、重复性好,可用于其质量控制。
An extension result for the Landau-Lifshitz equation with Neumann boundary condition

We establish an extension result of existence and partial regularity for the nonzero Neumann initial-boundary value problem of the Landau-Lifshitz equation with nonpositive anisotropy constants in three or four dimension space. The partial regularity is proved up to the boundary and this result is an important supplement to those for the Dirichlet problem or the homogeneous Neumann problem.
宣木瓜有效成分的研究进展

为了进一步研究和开发利用宣木瓜资源,本文重点介绍了宣木瓜的主要营养成分、生理活性物质的功能作用、含量,同时比较了宣木瓜和其他种类的木瓜在营养成分和生物功能物质上的差异。并针对宣木瓜可开发的相应产品进行了简单综述。
中医学的“时”不等于“时间”

中医学的"时"或"四时"是"天"的具体化,是指气以阴阳这一基本矛盾为动力的开放圆周式的运动。这种运动既表现出多彩的性质,又表现出复杂的功能;现在来看,应是时空合一。不能把现代西方哲学"朝着一个方向不可分割"的"时间一维"概念强加给中国传统文化;以"时间"解"时"的所谓"以时间为本位"是对中医学和中国文化的误读。
棉花半矮秆基因的定位

株高是农作物的重要农艺性状之一,植株过高容易引起倒伏减产,而矮生植株抗倒能力强,源、库、流关系协调,有利于提高作物的稳产性。矮秆品种通过塑造理想株型和合理密植,可实现单产水平的突破。在20世纪60~70年代,由矮化育种带来的"绿色革命"便是很好的例证。因此作物矮秆基因的发掘研究和利用也越来越受到科技界的普遍重视。
井抽水地下水直线运动规律探讨

与法国达西同时期的水力学者裘布依于1857年把达西德渗透定律应用到天然含水层中。得到了著名的裘布依微分方程。然而,它只能局限于某种特定的条件下去解释地下水运动规律。这个理论方程式无法处理和解释地下水在天然水力坡度的作用下,进入抽水井降落漏斗影响范围内的天然径流量这个客观事实,其计算结果可信度低。本文提出了渗透系数一种新的计算方法。渗透系数等于井管抽水单位涌水量除以所利用含水层厚度。
基于B/S模式的智能室间质量评价管理系统

目的开发与建立基于B/S(Browser/Server)模式的远程智能室间质量评价(external quality assessment,EQA)管理系统。方法医学检验专业人员从本专业出发,结合电子政务及电子商务理念,用动态服务器页面(active server page,ASP)、ASP.net、C#(C Sharp)、独立冗余磁盘阵列(redundant array of independent disk,RAID)等信息技术,面向医学检验实验室独立开发EQA管理系统。结果成功建立了一个智能化的EQA管理系统,该系统操作简单、运行速度快、数据传输可靠,实现了客户群不断扩大、灵活开放的扩展功能、多平台联用、数据保密性强以及智能化统计与数据挖掘在线自动完成等特点。结论基于B/S模式的智能EQA管理系统有利于临检中心对辖区内临床实验室的EQA。
Aversive and non-reward learning in the fire-bellied toad using familiar and unfamiliar prey stimuli

The present study investigated how snapping behavior toward familiar and unfamiliar prey is modified by reward omission and aversive conditioning in the fire-bellied toad Bombina orientalis. Toads were trained to snap at cricket images by rewarding them with live crickets. The task was learned, and the learning criterion (10 snapping responses within 2 minutes) was reached in all individuals investigated. Subsequent reward omission did not alter the frequency of snapping to the familiar cricket stimulus. Snapping decreased only in some individuals, when a mild foot shock was applied at snapping. However, at presentation of images of hitherto unfamiliar meal worms and foot-shock application at snapping to the stimulus, the majority of toads diminished snapping significantly. Snapping responses decreased more rapidly, when snapping at meal worms was not rewarded or a footshock was applied uncorrelated to the presentation of or snapping at meal worms. These results demonstrate that in toads familiarity and unfamiliarity of prey stimuli are important factors in aversive learning, because well-trained responses to familiar stimuli become immune against reward omission. Furthermore, at presentation of unfamiliar stimuli, omission of reward and uncorrelated footshock had a stronger aversive effect than correlated footshock.
Comprehension of functional support by enculturated chimpanzees Pan troglodytes

Studies of causal understanding of tool relationships in captive chimpanzees have yielded disparate findings, particularly those reported by Povinelli & colleagues (2000) for tool tasks by laboratory chimpanzees. The present set of experiments tested nine enculturated chimpanzees on three versions of a support task, as described by Povinelli (2000), during which food rewards were presented in different experimental configurations. In Experiment 1, stimulus pairs included a choice between a cloth with a reward on the upper right corner or with a second reward off the cloth, adjacent to a corner, with the second pair comprised of a cloth with food on the upper right corner, and a second cloth with the reward on the substrate, partially covered. All subjects were successful with both test conditions in Experiment 1. In a second study, the experimental choices included one of two possible correct options, paired with one of three incorrect options, with the three incorrect choices all involving varying degrees of perceptual containment. All nine chimpanzees scored significantly above chance across all six conditions. In Experiment 3, four unique conditions were presented, combining one of two possible correct choices with one of two incorrect choices. Six of the subjects scored significantly above chance across the four conditions, and group performance on individual conditions was also significant. Superior performance was demonstrated by female subjects in Experiment 3, similar to sex differences in tool use previously reported for wild chimpanzees and some tool tasks in captive chimpanzees. The present results for Experiments 2 & 3 were significantly differed from those reported by Povinelli et al. (2000) for laboratory-born, peer-reared chimpanzees. One contribution towards the dramatic differences between the two study populations may be the significant rearing and housing differences of the chimpanzee groups. One explanation is that under conditions of enculturation, rich social interactions with humans and conspecifics, as well as active exploration of artifacts, materials, and other aspects of their physical environment had a significant impact on the animals’ ability to recognize the support relationships among the stimulus choices. Overall, the present findings provide strong support for the hypothesis that our chimpanzee subjects based their responses on an understanding of functional support which represented one facet of their folk physics repertoire [Current Zoology 57 (4): 429–440, 2011].
Study on the effect of the infill walls on the seismic performance of a reinforced concrete frame

Motivated by the seismic damage observed to reinforced concrete (RC) frame structures during the Wenchuan earthquake, the effect of infill walls on the seismic performance of a RC frame is studied in this paper. Infill walls, especially those made of masonry, offer some amount of stiffness and strength. Therefore, the effect of infill walls should be considered during the design of RC frames. In this study, an analysis of the recorded ground motion in the Wenchuan earthquake is performed. Then, a numerical model is developed to simulate the infill walls. Finally, nonlinear dynamic analysis is carried out on a RC frame with and without infill walls, respectively, by using CANNY software. Through a comparative analysis, the following conclusions can be drawn. The failure mode of the frame with infill walls is in accordance with the seismic damage failure pattern, which is strong beam and weak column mode. This indicates that the infill walls change the failure pattern of the frame, and it is necessary to consider them in the seismic design of the RC frame. The numerical model presented in this paper can effectively simulate the effect of infill walls on the RC frame.
Evaluation of collapse resistance of RC frame structures for Chinese schools in seismic design categories B and C

According to the Code for Seismic Design of Buildings (GB50011-2001), ten typical reinforced concrete (RC) frame structures, used as school classroom buildings, are designed with different seismic fortification intensities (SFIs) (SFI=6 to 8.5) and different seismic design categories (SDCs) (SDC=B and C). The collapse resistance of the frames with SDC=B and C in terms of collapse fragility curves are quantitatively evaluated and compared via incremental dynamic analysis (IDA). The results show that the collapse resistance of structures should be evaluated based on both the absolute seismic resistance and the corresponding design seismic intensity. For the frames with SFI from 6 to 7.5, because they have relatively low absolute seismic resistance, their collapse resistance is insufficient even when their corresponding SDCs are upgraded from B to C. Thus, further measures are needed to enhance these structures, and some suggestions are proposed.
A discrete model for response estimation of soil-structure systems with embedded foundations

The need for simplifi ed physical models representing frequency dependent soil impedances has been the motivation behind many researches throughout history. Generally, such models are generated to capture impedance functions in a wide range of excitation frequencies, which leads to relatively complex models. That is while there is just a limited range of frequencies that really influence the response of the structure. Here, a new methodology based on the response-matching concept is proposed, which can lead to the development of simpler discrete models. The idea is then used to upgrade an existing simple model of surface foundations to the case of embedded foundations. The applicability of the model in both frequency domain and time domain analyses of soil-structure systems with embedded foundations is discussed. Moreover, the accuracy of the results is compared with another existing discrete model for embedded foundations.
Numerical simulation of the seismic behavior of self-centering steel beam-column connections with bottom flange friction devices

A new type of steel moment resisting frame with bottom flange friction devices (BFFDs) has been developed to provide self-centering capacity and energy dissipation, and to reduce permanent deformations under earthquakes. This paper presents a numerical simulation of self-centering beam-column connections with BFFDs, in which the gap opening /closing at the beam-column interfaces is simulated by using pairs of zero-length elements with compression-only material properties, and the energy dissipation due to friction is simulated by using truss elements with specified hysteretic behavior. In particular, the effect of the friction bolt bearing against the slotted plate in the BFFDs was modeled, so that the increase in lateral force and the loss of friction force due to the bolt bearing could be taken into account. Parallel elastic-perfectly plastic gap (ElasticPPGap) materials in the Open System for Earthquake Engineering Simulation (OpenSees) were used with predef ined gaps to specify the sequence that each bolt went into the bearing and the corresponding increase in bending stiffness. The MinMax material in OpenSees is used to specify the minimum and maximum values of strains of the ElasticPPGap materials. To consider the loss of friction force due to bolt bearing, a number of parallel hysteretic materials were used, and the failure of these materials in sequence simulated the gradual loss of friction force. Analysis results obtained by using the proposed numerical model are discussed and compared with the test results under cyclic loadings and the seismic loading, respectively.
RCMARS: Robustification of CMARS with different scenarios under polyhedral uncertainty set

Our recently developed CMARS is powerful in handling complex and heterogeneous data. We include into CMARS the existence of uncertainty about the scenarios. Indeed, data include noise in both output and input variables. Therefore, solutions of the optimization problem may reveal a remarkable sensitivity to perturbations in the parameters of the problem. The data uncertainty results in uncertain constraints and objective function. To overcome this difficulty, we refine our CMARS algorithm by a robust optimization technique proposed to cope with data uncertainty. In our previous study, we present the new robust CMARS (RCMARS) in theory and method and illustrate it with a numerical example. In this study, we present RCMARS results with different uncertainty scenarios for our numerical example.
Symmetry analysis and some exact solutions of cylindrically symmetric null fields in general relativity

The symmetry reduction method based on the Frechet derivative of the differential operators is applied to investigate symmetries of the Field equations in general relativity corresponding to cylindrically symmetric space–time, that is a coupled system of nonlinear partial differential equations of second order. More specifically, this technique yields invariant transformation that reduce the given system of partial differential equations to a system of nonlinear ordinary differential equations. Some of the reduced systems are further studied for exact solutions.
Nonlinear modeling and analysis of a rolling element bearing with a clearance

Rolling element bearings are the key components in many rotating machinery. For efficient performance of the machine it is necessary to accurately predict the effect of various parameters and operating conditions on the machine's behavior. This paper deals with the development of a nonlinear model of the rotor-bearing system on rolling element bearings with clearance. Clearance is an important nonlinearity which can cause bifurcations and chaos as has been shown in this paper. In this paper a detailed model for clearance is developed. In this model the inner race center and the outer race center are not assumed to be collinear when relations for deflections in the rolling element are developed. The model is non-dimensionalized and then analyzed to reveal rich nonlinear phenomena. Further, for better performance of any machine it is necessary to identify and stay out of chaotic regimes of operation. Hence, Lyapunov exponents and Poincare mappings are used to analyze the system and determine the regions of chaotic response.
Exponential stabilization using sliding mode control for singular systems with time-varying delays and nonlinear perturbations

This paper considers a sliding mode control (SMC) of singular systems. The systems under consideration involve nonlinear perturbations and time-varying delays. The aim of this paper is to design a sliding mode controller such that the nonlinear singular system is exponentially stable and its trajectory can be driven onto the sliding surface in finite time. By using the Lyapunov–Krasovskii functional and some specified matrices, conditions on exponential stabilization are obtained in the form of strict linear matrix inequalities (LMIs). A numerical example is given to illustrate the effectiveness of the proposed main results. All these results are expected to be of use in the study of singular time-varying delay systems with nonlinear perturbations.
Stochastic global exponential stability for neutral-type impulsive neural networks with mixed time-delays and Markovian jumping parameters

This paper investigates the problem of the global exponential stability for neutral-type impulsive neural networks with mixed delays and Markovian jumping parameters. The mixed delays include discrete and distributed time-delays and the jumping parameters are generated from a continuous time discrete state homogenous Markov process. Based on the Lyapunov functional, a sufficient criterion is derived in terms of linear matrix equality (LMI).
On an approximate method for the delay logistic equation

This note concerns with the asymptotic properties of solutions of the delay logistic equation. In particular, we point out some false statements in the recent paper Khan et al. [Khan H, Liao SJ, Mohapatra RN, Vajravelu K. An analytical solution for a nonlinear time-delay model in biology. Commun Nonlinear Sci Numer Simulat 2009;14:3141–3148]. Moreover, we show that the author’s method is not able to reveal the basic and important features of the dynamics of the delay logistic equation, and gives misleading results.