检索结果-南通市图书馆

The effect of a curved bed on the discharge equation in a spillway with a breast wall

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2015年第2期27卷 311-318页

作者： nguyen Cong-thanh 王玲玲唐洪武 State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering College of Water Conservancy and Hydropower Engineering Hohai University

The flow through a breast wall spillway is greatly affected by the centripetal force due to a downstream curved profile. Therefore, the mean vertical pressure distribution at the outlet section is not consistent with the hydrostatic pressure law. This distribution in turn affects the discharge capacity of the breast wall spillway. This paper experimentally studies the effect of a convex downstream profile on the mean pressure variation and the discharge of a breast wall spillway without gates. It is indicated that the effect of the curvilinear streamline on the mean vertical pressure variation is significant. The regression analysis method is used to determine the water head effect Z o of the orifice opening through the mean pressure variation. A discharge prediction formula of the breast wall spillway is obtained under the limited conditions of a laboratory flume. The predicted discharge is compared to the measured discharge. A good agreement is evidenced for the free orifice flow with errors within ？5%, while a big error（20% or even more） is obtained if the hydrostatic pressure law is used for the determination of Zo.

关键词： curved bed spillway breast wall multiple linear regression orifice flow mean pressure distribution

Study of vertically ascending flight of a hawkmoth model

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2020年第5期36卷 1031-1045,I0002页

作者： Anh Tuan nguyen Vu Dan thanh Le The Hung Tran V.n.Due Van Binh Phung Faculty of Aerospace Engineering Le Quy Don Technical UniversityHanoiVietnam Institute of Theoretical and Applied Research.Duy Tan University HanoiVietnam Division of Construction Computation Institute for Computational ScienceTon Due Thang UniversityHo Chi Minh CityVietnam Faculty of Civil Engineering Ton Due Thang UniversityHo Chi Minh CityVietnam

This paper provides insight into the wing kinematics,the power requirement and the dynamic stability characteristics of a hawkmoth model in vertically ascending *** wing kinematics of the hawkmoth model is obtained based on the minimum required power *** optimization process is conducted using genetic and simplex algorithms that are coupled with an artificial neural network to rapidly predict the aerodynamic force and required *** training data for the neural network are generated from an unsteady vortex-lattice *** to hover,the results in this study show the larger flapping frequency and the smaller rotation amplitude of the hawkmoth wing kinematics in ascending ***,more power is required when the ascending speed *** conducting a dynamic modal analysis based on a cycle-average approach,the certain effect of the ascending speed on the modal structures of the hawkmoth model was observed.

关键词： Hawkmoth Ascending flapping flight-Genetic algorithm Artificial neural network Flight dynamic stability

Using Adaptive Gain Scheduling LQR Method Control of Arm Driven Inverted Pendulum System Based on PIC18F4431

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Harbin Institute of Technology(new Series) 2013年第4期20卷 85-92页

作者： Huu Chan thanh nguyen An-Wen Shen Department of Control Science and Engineering HuaZhong University of Science and Technology

The arm driven inverted pendulum system is a highly nonlinear model, muhivariable and absolutely unstable dynamic system so it is very difficult to obtain exact mathematical model and balance the inverted pendulum with variable position of the ann. To solve this problem, this paper presents a mathematical model for arm driven inverted pendulum in mid-position configuration and an adaptive gain scheduling linear quadratic regulator control method for the stabilizing the inverted pendulum. The proposed controllers for arm driven inverted pendulum are simulated using MATLAB-SIMULInK and implemented on an experiment system using PIC 18F4431 mieroeontroller. The result of experiment system shows the control performance to be very good in a wide range stabilization of the arm position.

关键词： Arm Driven Inverted Pendulum (ADIP) adaptive gain scheduling LQR control LQR control swing up pendlum

A comparative analysis of weight-based machine learning methods for landslide susceptibility mapping in Ha Giang area

在线全文

学校读者我要写书评

暂无评论

Big Earth Data 2023年第4期7卷 1005-1034页

作者： thanh Trinh Binh thanh Luu Trang Ha Thi Le Duong Huy nguyen Trong Van Tran Thi Hai Van nguyen Khanh Quoc nguyen Lien Thi nguyen Faculty of Computer Science Phenikaa UniversityYen NghiaHa DongHanoi 12116Vietnam Phenikaa Research and Technology Institute(PRATI) A&A Green Phoenix Group JSCNo.167 Hoang NganTrung HoaCau GiayHanoi 11313Vietnam northwestern Geological Division General Department of Geology and Minerals of VietnamHanoiVietnam Youth union office Thuyloi University175 Tay SonDong DaHanoiVietnam Center of Remote Sensing and Geohazards Vietnam Institute of Geosciences and Mineral ResourcesHanoiVietnam

Landslide susceptibility maps (LSMs) are very crucial for planningpolicies in hazardous areas. However, the accuracy and reliability ofLSMs depend on available data and the selection of suitable *** study is conducted to produce LSMs by combinations of machinelearning methods and weighting techniques for Ha Giang province,Vietnam, where has limited data. In study area, we gather 11 landslideconditioning factors and establish a landslide inventory *** the weights of classes (or factors) is very important toprepare data for machine learning methods to generate LSMs. Wefrst use frequency ratio (FR) and analytic hierarchy process (AHP)techniques to generate the weights. Then, random forest (RF), supportvector machine (SVM), logistic regression (LR), and AHP methods arecombined with FR and AHP weights to yield accurate and reliableLSMs. Finally, the performance of these methods is evaluated by fivestatistical metrics, ROC and R-index. The empirical results have shownthat RF is the best method in terms of R-index and the five metrics, *** rate (0.9661), FP rate (0.0), ACC (0.9835), MAE (0.0046), and RMSE(0.0350) for this study area. This study opens the perspective of weightbasedmachine learning methods for landslide susceptibility mapping.

关键词： Landslide logistic regression random forest SvM Vietnam

On the Laws of Large numbers for Double Arrays of Independent Random Elements in Banach Spaces

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2014年第8期30卷 1353-1364页

作者： Andrew ROSALSKY Le Van thanh nguyen Thi THUY Department of Statistics University of FloridaGainesville Department of Mathematics Vinh University

For a double array of independent random elements {Vmn,m ≥ 1,n ≥ 1} in a real separable Banach space,conditions are provided under which the weak and strong laws of large numbers for the double sums mi=1 nj=1Vij,m ≥ 1,n ≥ 1 are *** the identically distributed and the nonidentically distributed cases are *** the main theorems,no assumptions are made concerning the geometry of the underlying Banach *** theorems are applied to obtain Kolmogorov,Brunk–Chung,and Marcinkiewicz–Zygmund type strong laws of large numbers for double sums in Rademacher type p（1 ≤ p ≤ 2） Banach spaces.

关键词： Real separable Banach space double array of independent random elements strong and weak laws of large numbers almost sure convergence convergence in probability Rademacher type p Banach space

The mechanism and effects of subgrade fluidisation under ballasted railway tracks

在线全文

学校读者我要写书评

暂无评论

Railway Engineering Science 2020年第2期28卷 113-128页

作者： Buddhima Indraratna Mandeep Singh thanh Trung nguyen Centre for Geomechanics and Railway Engineering University of WollongongWollongong CityNSW 2522Australia Australian Research Council(ARC)Industrial Transformation Training Centre ITTC-RailUniversity of WollongongWollongong CityNSW 2522Australia

The rapid growth in railway infrastructure and the construction of high-speed heavy-haul rail network,especially on ground that is basically unsuitable,poses challenges for geotechnical engineers because a large part of the money invested in the development of railway lines is often spent on track *** fact around the world,the mud pumping of subgrade fines is one of the common reasons why track performance deteriorates and track stability is *** article presents a series of laboratory tests to examine following aspects of mud pumping:(1)the mechanisms of subgrade fluidisation under undrained condition,(2)the effects of mud pumping on the engineering characteristics of ballast,and(3)the use of vertical drains to stabilize subgrade under cyclic *** undrained cyclic triaxial testing on vulnerable soft subgrade was performed by varying the cyclic stress ratio(CSR)from 0.2 to 1.0 and the loading frequency f from 1.0 to 5.0 *** is seen from the test results that for a specimen compacted at an initial dry density of 1790 kg/m3,the top portion of the specimen fluidises at CSR=0.5,irrespective of the applied loading *** cyclic railway loading,the internal redistribution of water at the top of the subgrade layer softens the soil and also reduces its *** response to these problems,this paper explains how the inclusion of vertical drains in soft subgrade will help to prevent mud pumping by alleviating the build-up of excess pore pressures under moving train loads.

关键词： Mud pumping Ballasted track Subgrade fluidisation Fouled ballast Prefabricated vertical drains

Optimization Agricultural Supply Chain:A Case Study of Fertilizer Supplier Selection

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2022年第8期72卷 4057-4068页

作者： nguyen Van thanh nguyen Thi Kim Lan Syed Tam Husain nguyen Hoang Hai nguyen Viet Tinh Faculty of Commerce Van Lang UniversityHo Chi Minh CityVietnam International Education Institute Van Lang UniversityHo Chi Minh CityVietnam

The 21st century is associated with the IndustrialRevolution 4.0 and the organic agriculture trend,making the utilization of high-quality fertilizers,abundant nutritional content,economical,and no affect to environment *** to the new concept,clean agricultural production and organic agricultural products are not allowed to excessively use synthetic chemicals such as chemical fertilizers,and plant protection drugs,but priority is to use manure,organic fertilizers,and natural mineral *** must meet the balanced nutritional requirements of crops,maintain,and improve the fertility of the ground,protect the surrounding ecosystem,and leave harmful effects in agricultural products,products with high quality,safe for users and high economic efficiency for *** achieve the above goal,the selection of a fertilizer supplier is an important decision,supporting the supply chain’s sustainable development,fertilizer supplier selection is a multicriteria decision making model,the decision maker must assess all qualitative and quantitative *** this paper,the author proposed an integer decision making model including Fuzzy Analytic Hierarchy Process(FAHP)and Complex Proportional Assessment of Alternatives(COPRAS)for fertilizer supplier *** weightings of the criteria are calculated by using FAHP,COPRAS is then applied for ranking some potential fertilizer *** efficiency of the proposed models is proved by a case study conducted in a farm located in the south of *** research is the first fertilizer supplier evaluation and se-lection model in Vietnam by interviewing experts and reviewing the ***-search result is to provide a case study on evaluating supplier in agricultural supply chain utilizing the model proposed by the combination of FAHP and COPRAS models.

关键词： Fertilizer industry optimization model fuzzy theory agricultural supply chain

Engine performance and combustion characteristics of a direct injection compression ignition engine fueled waste cooking oil synthetic diesel

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Coal Science & Technology 2020年第3期7卷 560-570页

作者： thanh Viet nguyen Khanh Duc nguyen nang Xuan Ho Vinh Duy nguyen Department of Internal Combustion Engine School of Transportation EngineeringHanoi University of Science and TechnologyHanoiViet Nam Faculty of Vehicle and Energy Engineering Phenikaa UniversityYen NghiaHa-Dong DistrictHanoiViet Nam

Biodiesels produced from various feedstocks have been considered as alternative fuels used in internal combustion engines without major *** research focuses on producing biodiesel from waste cooking oil(WCOSD)by the catalytic cracking method using MgO as the catalyst and comparing the engine operating characteristics of the test engine when using WCOSD and traditional diesel(CD)as test *** a result,the brake power of the test engine fueled WCOSD,and traditional diesel is ***,the engine fuel consumption in the case of using WCOSD is slight increases in some operating ***,the nitrogen oxides emissions of the test engine fueled WCOSD are higher than those of CD at all tested *** trend is opposite for hydrocarbon emission as the HC emission of the engine fueled by WCOSD reduces 26.3%on *** smoke emission of the test engine in case of using WCOSD is lower 17%on average than that of ***,the carbon monoxide emissions are lower at the low and medium loads and higher at the full *** results show that the new biodiesel has the same characteristics as those of commercial biodiesel and can be used as fuel for diesel engines.

关键词： Feedstock Waste cooking oil Engine characteristics Exhaust missions Ignition timing Fuel consumption

Comparative mammalian cell cytotoxicity of wastewater with elevated bromide and iodide after chlorination,chloramination, or ozonation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2017年第8期29卷 296-301页

作者： Shengkun Dong thanh H.nguyen Michael J.Plewa Department of Civil and Environmental Enoineering University of Illinois at Urbana-Champaign Urbana IL 61801 USA Department of Crop Sciences University of Illinois at Urbana-Champaign Urbana IL 61801 USA Safe Global Water Institute Uniuersity of Illinois at Urbana-Champaign Urbana IL 61801 USA

Recycling wastewater is becoming more common as communities around the world try to better control their water resources against an increased frequency of either prolonged droughts or intense flooding. For communities in coastal areas, wastewaters may contain elevated levels of bromide（Br^-） and iodide（I^-） from seawater intrusion or high mineral content of source waters. Disinfection of such wastewater is mandatory to prevent the spread of pathogens, however little is known about the toxicity of wastewater after disinfection in the presence of Br^-and I^-. In this study we compared the induction of chronic cytotoxicity in mammalian cells in samples of municipal secondary wastewater effluent amended with elevated levels of Br^-/I^-after disinfection by chlorine, chloramines or ozone to identify which disinfection process generated wastewater with the lowest level of adverse biological response. Chlorination increased mammalian cell cytotoxicity by 5times as compared to non-disinfected controls. Chloramination produced disinfected wastewater that expressed 6.3 times more cytotoxicity than the non-disinfected controls and was 1.3 times more cytotoxic than the chlorinated samples. Ozonation produced wastewater with cytotoxicity comparable to the non-disinfected controls and was at least 4times less cytotoxic than the chlorine disinfected wastewaters. These results indicate that compared to chlorination and chloramination, ozonation of wastewater with high Br^-/Ilevels yielded the lowest mammalian cell cytotoxicity, suggesting its potential as a more favorable method to disinfect wastewater with minimizing the biological toxicity in mind.

关键词： Cytotoxicity Ozonation Chlorination Chloramination Wastewater Bromide Iodide Disinfection