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Climate Trends and Their Impact on Sorghum Production in Marigat, Baringo County: A Historical Analysis

Open Journal of Modern Hydrology 2024年第2期14卷 106-129页

作者： Kennedy O. Okuku Japheth O. Onyando Romulus O. Okwany Clement K. Kiptum Department of Agricultural Engineering Egerton University Nakuru Kenya School of Engineering University of Eldoret Eldoret Kenya

Climate is subject to fluctuations in the majority of the world, mainly caused by rainfall as well as temperature variations. Climate fluctuations in Kenya have resulted in the spread of desert-like conditions in the ASALs region, such as Marigat in Baringo County. As a county, Baringo experiences great variations in climate annually, as well as uncertainty in expected rains, thereby negatively impacting the production of crops such as sorghum. This study applied the rainfall anomaly index (RAI), standardised precipitation evapotranspiration index (SPEI), standard precipitation index (SPI), and Mann-Kendall (MK) statistical test for trends on historical climatic data in analysing both temperature and precipitation data over the period 1990 to 2022 to determine their trend, patterns and how they affect the production of sorghum crops. The machine learning method (R studio) with inputs was used to calculate the SPI, SPEI, RAI and MK trend test. The rainfall varied from below average to above average during the study period with no clear pattern in the RAI, SPEI and SPI values. The years 2020 and 2000 stood out as they had higher and lower rainfall than usual, respectively. The Marigat area generally experienced more rainfall during the high/long rainfall season (AMJJ). The MK trend test on average monthly rainfall, SOND, AMJJ, and annual precipitation confirmed a positive trend in precipitation. However, the short rainy season (SOND) was found to be the most variable period for rainfall, and there was a slight increase in daily average temperatures during this season.

关键词： Trends precipitation Temperature RAI SPI SPEI and MK

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Evaluation of Rainfall Tendency for the Twentieth Century over Indira Sagar Region in Central India

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American Journal of Climate Change 2024年第1期13卷 47-68页

作者： Rituraj Shukla Deepak Khare Ramesh P. Rudra Priti Tiwari Himanshu Sharma Prasad Daggupati Pradeep Goel School of Engineering University of Guelph Guelph Canada Department of Water Resources Development and Management Indian Institute of Technology Roorkee India Indira Gandhi Agricultural University Raipur India Department of Civil Engineering Institute of Infrastructure Technology Research and Management (IITRAM) Ahmedabad India

The study investigates long-term changes in annual and seasonal rainfall patterns in the Indira Sagar Region of Madhya Pradesh, India, from 1901 to 2010. Agriculture sustainability, food supply, natural resource development, and hydropower system reliability in the region rely heavily on monsoon rainfall. Monthly rainfall data from three stations (East Nimar, Barwani, and West Nimar) were analyzed. Initially, the pre-whitening method was applied to eliminate serial correlation effects from the rainfall data series. Subsequently, statistical trends in annual and seasonal rainfall were assessed using both parametric (student-t test) and non-parametric tests [Mann-Kendall, Sen’s slope estimator, and Cumulative Sum (CUSUM)]. The magnitude of the rainfall trend was determined using Theil-Sen’s slope estimator. Spatial analysis of the Mann-Kendall test on an annual basis revealed a statistically insignificant decreasing trend for Barwani and East Nimar and an increasing trend for West Nimar. On a seasonal basis, the monsoon season contributes a significant percentage (88.33%) to the total annual rainfall. The CUSUM test results indicated a shift change detection in annual rainfall data for Barwani in 1997, while shifts were observed in West and East Nimar stations in 1929. These findings offer valuable insights into regional rainfall behavior, aiding in the planning and management of water resources and ecological systems.

关键词： precipitation Parametric Non-Parametric Tests Trend Analysis Serial Correlations

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Climate trends in tropical cyclone-induced precipitation and wind over Shanghai

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Tropical Cyclone Research and Review 2022年第3期11卷 219-224页

作者： Lina Bai Rijin Wan Rong Guo Ming Ying Rui Jin Shanghai Typhoon Institute China Meteorological AdministrationShanghaiChina Asia-Pacific Typhoon Collaborative Research Center ShanghaiChina

The trends in annual precipitation and wind induced by tropical cyclones(TCs)over Shanghai during the last 40 years are estimated.Results indicate that there is a significant increasing trend in the annual total precipitation induced by TCs,which is related to the significant positive trends in daily precipitation and annual torrential rain days.Meanwhile,a significant decreasing trend shows in maximum sustained wind,which seems to be related to the downward trend in the intensity of TCs when affecting Shanghai.The annual frequencies of affected TCs,TC translation speed and distance from Shanghai when affecting Shanghai have no obvious tendency.The different trends in precipitation and wind suggested that a more comprehensive metric for assessing TCs'influence on society is necessary.

关键词： Tropical cyclone precipitation Wind Climate trend Shanghai

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precipitation transformation of rare earth sulfate into chloride with p-dodecylphenoxy carboxylic acids

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Journal of Rare Earths 2019年第12期37卷 1326-1333页

作者： Yanliang Wang Jia Su Xiangguang Guo Jianguo Cui Yan Bai Fujian Li Xiaoqi Sun CAS Key Laboratory of Design and Assembly of Functional Nanostructures and Fujian Key Laboratory of NanomaterialsFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China University of Chinese Academy of Sciences Beijing 100039China Baotou Research Institute of Rare Earths Baotou 014010China State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China Ganzhou Rare Earth Group Co. Ltd.Ganzhou 34WOOChina

Methods for transforming rare earth(RE)sulfate into chloride mainly include extraction process with organophosphonic mono-acids or aliphatic acids and precipitation process with ammonium bicarbonate(NH4 HCO3).In this paper,alkylphenoxy carboxylic acids(HAs)ofp-dodecylphenoxy acetic acid(HA-Ⅰ),pdodecylphenoxypropanoic acid(HA-Ⅱ)and p-dodecylphenoxybutyric acid(HA-Ⅲ),which were liquid at room temperature were synthesized and characterized.The precipitation mechanisms of RE elements with the HAs were investigated and the HA/RE molar ratios of the solid complexes were determined as3:1 by equi-molar series method which accord with the principle of charge balance.Applicability of HAs for the transformation of RE sulfate from concentrated sulfuric acid roasted RE concentrate into chloride via precipitation method was discussed.100%HA-Ⅱwas selected as the liquid organic precipitant without dilution of volatile solvent soracceleration of phase separation by phase-modifiers.The RE sulfate solution can be precipitated by HA-Ⅱafter neutralization with liquid NaOH and stripped with concentrated HCl at room temperature.High concentration of RE chloride of 218.1 g/L with low residue of sulfate radical of 0.536 g/L was obtained.The residual organic precipitant in the raffinate solution was tested to be lower than 8 mg/L at 25℃and the chemical oxygen demand(COD)in wastewater was less than 50 mg/L.

关键词： Rare earth Dodecylphenoxycarboxylic acid Recovery precipitation Transformation

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precipitation and stability of reversed austenite in 9Ni steel

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International Journal of Minerals,Metallurgy and Materials 2010年第5期17卷 587-595页

作者： Yue-hui Yang Qing-wu Cai Di Tang Hui-bin Wu Research Institute of Metallurgical Engineering University of Science and Technology Beijing Beijing 100083 China

A new method was used to analyze the factors affecting the precipitation of reversed austenite during tempering. The samples were kept at various tempering temperatures for 10 min and their length changes were recorded. Then, the precipitation of reversed austenite which led to the length reduction was shown by thermal expansion curves. The results show that the effects of process parameters on the precipitation of reversed austenite can be determined more accurately by this method than by X-ray diffraction. When the quenching and tempering process is adopted, both the lower quenching temperature and higher tempering temperature can promote the precipitation of reversed austenite during tempering; and when the quenching, lamellarizing, and tempering process is used, intercritical quenching is considered beneficial to the precipitation of reversed austenite in the subsequent tempering because of Ni segregation during holding at the intercritical temperature.

关键词： cryogenic equipment low carbon steel reversed austenite precipitation stability thermal expansion measurement

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precipitation and responding damping behavior of heat-treated AZ31 magnesium alloy

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Acta Metallurgica Sinica(English Letters) 2009年第1期22卷 1-6页

作者： Diqing WAN Jincheng WANG Gaifang WANG Lin LIN Zhigang FENG Gencang YANG State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi＇an 710072China

Microstructure observation and dynamic mechanical analysis were carried out to investigate the precipitation and responding damping behaviors of AZ31 magnesium alloy. All the strain amplitude-dependent damping curves of the aged alloys are located between the curves of solutionized and as-cast alloys, although they have different critical strain amplitudes. The G-L theory is employed to explain the damping mechanism involving the interaction between the dislocation and the precipitated phase. In addition, a damping peak is observed at temperatures close to 330 ℃ for AZ31 magnesium alloy, which is related to the β-MglTA112 phase dissolution.

关键词： Magnesium alloys Damping behavior precipitation G-L model Damping peak

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precipitation behavior and martensite lath coarsening during tempering of T/P92 ferritic heat-resistant steel

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International Journal of Minerals,Metallurgy and Materials 2014年第5期21卷 438-447页

作者： Lin-qing Xu Dan-tian Zhang Yong-chang Liu Bao-qun Ning Zhi-xia Qiao Ze-sheng Yan Hui-jun Li State Key Lab of Hydaulic Engineering Simulation and Safety School of Material Science and EngineeringTianjin University School of Materials Science and Engineering Tianjin University of Technology School of Mechanical Engineering Tianjin University of Commerce

Tempering is an important process for T/P92 ferritic heat-resistant steel from the viewpoint of microstructure control, as it facili- tates the formation of final tempered martensite under serving conditions. In this study, we have gained deeper insights on the mechanism underlying the microstructural evolution during tempering treatment, including the precipitation of carbides and the coarsening of martensite laths, as systematically analyzed by optical microscopy, transmission electron microscopy, and high-resolution transmission electron mi- croscopy. The chemical composition of the precipitates was analyzed using energy dispersive X-ray spectroscopy. Results indicate the for- mation of M3C （cementite） precipitates under normalized conditions. However, they tend to dissolve within a short time of tempering, owing to their low thermal stability. This phenomenon was substantiated by X-ray diffraction analysis. Besides, we could observe the precipitation of fine carbonitrides （MX） along the dislocations. The mechanism of carbon diffusion controlled growth of M23C6 can be expressed by the Zener＇s equation. The movement of Y-junctions was determined to be the fundamental mechanism underlying the martensite lath coarsening process. Vickers hardness was estimated to determine their mechanical properties. Based on the comprehensive analysis of both the micro- structural evolution and hardness variation, the process of tempering can be separated into three steps.

关键词： ferritic steel heat resisting tempering precipitation martensite coarsening

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precipitation analysis of as-cast HK40 steel after isothermal aging

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International Journal of Minerals,Metallurgy and Materials 2017年第10期24卷 1125-1133页

作者： M.L. Saucedo-Munoz A. Ortiz-Mariscal V.M. Lopez-Hirata J.D. Villegas-Cardenas Orlando Soriano-Vargas Erika O. Avila-Davila Instituto Politecnico Nacional (ESIQIE) Apdo. Postal 118-395 Mexico D.F. 07300 Universidad Politecnica Metepec y Tultitlan Edo. Mex. Mexico Tecnológico de Estudios Superiores de Jocotitlan Jocotitlan Edo. Mex. Mexico

As-cast HK40 steel was aged at 700, 800, or 900℃ for times as long as 2000 h. Microstructural characterization showed that the primary M_7C_3 carbide network contained a substantial content of manganese, in agreement with the microsegregation of manganese calculated by Thermo-Calc using the Scheil–Gulliver module. The dissolution of primary carbides caused the solute supersaturation of austenite and subsequent precipitation of fine M_(23)C_6 carbides in the austenite matrix for aged specimens. During prolonged aging, the carbide size increased with increasing time because of the coarsening process. A time–temperature–precipitation diagram for M_(23)C_6 carbides was calculated using the Thermo-CalcPRISMA software; this diagram showed good agreement with the experimental growth kinetics of precipitation. The fine carbide precipitation caused an increase in hardness; however, the coarsening process of carbides promoted a decrease in hardness. Nanoindentation tests of the austenite matrix indicated an increase in ductility with increasing aging time.

关键词： as-cast HK40 steel carbide precipitation aging precipitation simulation

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precipitation study of CO2-loaded glycinate solution with the introduction of ethanol as an antisolvent

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Frontiers of Chemical Science and Engineering 2020年第3期14卷 415-424页

作者： Siming Chen Yue Wu Geoffrey WStevens Guoping Hu Wenshou Sun Kathryn AMumford College of Environmental Sciences and Engineering Qingdao UniversityQingdao 266071China Peter Cook Centre for Carbon Capture and Storage Research(PCC) Particulate Fluids Processing Centre(PFPC)Department of Chemical EngineeringUniversity of MelbourneParkvilleVictoria 3010Australia

Focused beam reflectance measurement(FBRM)and 13C nuclear magnetic resonance(13C NMR)analysis were used to study the precipitation process of CO2-loaded potassium glycinate(KGLY)solutions at different CO2 loadings,during the addition of ethanol as an antisolvent at a rate of 10 mL·min−1.The volume ratio of ethanol added to the KGLY solution(3.0 mol·L−1,340 mL)ranged from 0 to 3.0.Three solid-liquid-liquid phases were formed during the precipitation process.The FBRM results showed that the number of particles formed increased with CO2 loading and ethanol addition for CO2-unsaturated KGLY solutions,whilst for CO2-saturated KGLY solution it first increased then decreased to a stable value with ethanol addition.13C NMR spectroscopic analysis showed that the crystals precipitated from the CO2-unsaturated KGLY solutions consisted of glycine only,and the quantity crystallised increased with CO2 loading and ethanol addition.However,a complex mixture containing glycine,carbamate and potassium bicarbonate was precipitated from CO2-saturated KGLY solution with the maximum precipitation percentages of 94.3%,31.4%and 89.6%,respectively,at the ethanol volume fractions of 1.6,2.5 and 2.3.

关键词： crystallization precipitation glycinate FBRM 13C NMR

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precipitation behavior of Ti in high strength steels

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Journal of Central South University 2017年第12期24卷 2767-2772页

作者：吴思炜刘振宇周晓光杨浩王国栋 State Key Laboratory of Rolling Technology and Automation Northeastern University Shenyang 110819 China

precipitation behavior of Ti in high strength steels was investigated by means of the equilibrium solid solubility theory. The contributions of Ti content to yield strength were calculated. The calculated results were verified by the hot rolling experiment for C–Mn steel and C–Mn–Ti micro alloyed steel, respectively. The research results show that the precipitates are mainly Ti N at the higher temperature. With the decreasing temperature, the proportion of Ti C in precipitates increases gradually. When the temperature drops to 800 °C, Ti C will become predominant for the precipitation of Ti. When Ti content is less than 0.014%(mass fraction), Ti has little influence on the yield strength. When Ti content is in the range of 0.014%–0.03%(mass fraction), the yield strength of Ti micro alloyed steel is greatly increased, which leads to instability of the mechanical properties of the steel. Therefore, the design of Ti content in high strength steels should avoid this Ti content range. When Ti content is higher than 0.03%, the yield strength increases stably. In this experiment, when added Ti content was controlled in the range of 0.03%–0.05%, the contribution to the yield strength of Ti micro alloyed steel can reach about 92.44 MPa.

关键词： precipitation strengthening solid solubility Ti(C, N) yield strength high strength steel

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