Study on Surface Plotting Methods in Parts Plotting

According to the factors that confirm the shape of surface, it is classified into two categories： arc surface and curve surface The method to confirm the category of surfaces and the plotting methods are discussed in this paper, which provide guidance for parts plotting.

Study on Chaotic Characteristics of the Friction Process between High Hardness Alloy Steel and Cemented Carbide under C60 Nanoparticle Fluid Lubrication

Friction and wear phenomenon is a complex nonlinear system,and it is also a significant problem in the process of metal cutting.In order to systematically analyze the friction and wear process of tool material-workpiece material friction pair in the cutting process of high hardness alloy steel under different lubrication conditions,the chaotic characteristics of friction process between high hardness alloy steel and cemented carbide under the lubrication C60 nano-particles fluid are studied based on the chaos theory.Firstly,the friction and wear experiments of the friction pair between high hardness alloy steel and cemented carbide tool are carried out based on the ring-block friction and wear tester,and the results of friction force signal in time domain and wear width are obtained.Then,the friction signals in time domain are processed and transformed based on phase space reconstruction and recurrence plot theory,and the recurrence plots of different experimental groups under different lubrication conditions are generated.The evolution law of recurrence plot is further observed and studied,and the recursive quantitative index is analyzed.Finally,the cutting experiments of tool wear are carried out.The results show that the proposed method can intuitively and accurately reveal the wear evolution process and the wear feature identification law of the tool material-high hardness alloy steel pair under different lubrication conditions.Meanwhile,it is found that when the concentration of C60 nanoparticles is 200∼300 ppm,the stability of the friction pair system is best.The proposed method can provide a strategy for wear prediction in cutting process,and provide a theoretical basis and technical support for antifriction lubrication methods in practical cutting applications.

Predicting Rock Burst in Underground Engineering Leveraging a Novel Metaheuristic-Based LightGBM Model

Rock bursts represent a formidable challenge in underground engineering,posing substantial risks to both infrastructure and human safety.These sudden and violent failures of rock masses are characterized by the rapid release of accumulated stress within the rock,leading to severe seismic events and structural damage.Therefore,the development of reliable prediction models for rock bursts is paramount to mitigating these hazards.This study aims to propose a tree-based model—a Light Gradient Boosting Machine(LightGBM)—to predict the intensity of rock bursts in underground engineering.322 actual rock burst cases are collected to constitute an exhaustive rock burst dataset,which serves to train the LightGBMmodel.Two population-basedmetaheuristic algorithms are used to optimize the hyperparameters of the LightGBM model.Finally,the sensitivity analysis is used to identify the predominant factors that may incur the occurrence of rock bursts.The results show that the population-based metaheuristic algorithms have a good ability to search out the optimal hyperparameters of the LightGBM model.The developed LightGBM model yields promising performance in predicting the intensity of rock bursts,with which accuracy on training and testing sets are 0.972 and 0.944,respectively.The sensitivity analysis discloses that the risk of occurring rock burst is significantly sensitive to three factors:uniaxial compressive strength(σc),stress concentration factor(SCF),and elastic strain energy index(Wet).Moreover,this study clarifies the particular impact of these three factors on the intensity of rock bursts through the partial dependence plot.

Computer plotting of multisystem p-T, T-X, p-X phase diagrams

As a continuation to the work reported by Yin in 1992, a new procedure is presented for computer plotting of the stable equilibrium phase diagram of an n-component system composed of (n + k) stoichiometric phases (or fluid species) where 2≤k≤4. The main points of the procedure are: (i) using the technique of sequential-absence of phases (SAP) to determine the possible invariant and univariant assemblages in a given multisystem; (ii) using the matrix inverse technique to generate and balance the univariant reactions from the corresponding univariant assemblages; (iii) comparing the phase assemblage at each invariant point with that of each univariant reaction to select the univariant curves about the corresponding invariant point; (iv) locating the invariant points with the technique of finding common equilibrium relation (CER); (v) using the sign function matrix (SFM) technique to discriminate between the stable portion of a univariant curve and its metastable extension about the corresponding

Parameter Identification of Structural Nonlinearity by Using Response Surface Plotting Technique

With rigorous dynamic performance of mechanical products,it is important to identify dynamic parameters exactly.In this paper,a response surface plotting method is proposed and it can be applied to identify the dynamic parameters of some nonlinear systems.The method is based on the principle of harmonic balance method(HBM).The nonlinear vibration system behaves linearly under the steady-state response amplitude,which presents the equivalent stiffness and damping coefficient.The response surface plot is over two-dimensional space,which utilizes excitation as the vertical axis and the frequency as the horizontal axis.It can be applied to observe the output vibration response data.The modal parameters are identified by the response surface plot as linearity for different excitation levels,and they are converted into equivalent stiffness and damping coefficient for each resonant response.Finally,the HBM with first-order expansion is utilized for identification of stiffness and damping coefficient of nonlinear systems.The classical nonlinear systems are applied in the numerical simulation as the example,which is used to verify its effectiveness and accuracy.An application of this technique for nonlinearity identification by experimental setup is also illustrated.

Recognition of dynamically varying PRI modulation via deep learning and recurrence plot

Recognition of pulse repetition interval(PRI)modulation is a fundamental task in the interpretation of radar intentions.However,the existing PRI modulation recognition methods mainly focus on single-label classification of PRI sequences.The prerequisite for the effectiveness of these methods is that the PRI sequences are perfectly divided according to different modulation types before identification,while the actual situation is that radar pulses reach the receiver continuously,and there is no completely reliable method to achieve this division in the case of non-cooperative reception.Based on the above actual needs,this paper implements an algorithm based on the recurrence plot technique and the multi-target detection model,which does not need to divide the PRI sequence in advance.Compared with the sliding window method,it can more effectively realize the recognition of the dynamically varying PRI mo dulation.

Combining descriptor-based analyses and mean-field modeling of the electrochemical interface to comprehend trends of catalytic processes at the solid/liquid interface

Electrocatalysis is undergoing a renaissance due to its central importance for a sustainable energy economy,relying on green(electro-)chemical processes to harvest,convert,and store energy.Theoretical considerations by electronic structure methods are key to identify potential material motifs for electrocatalytic processes at the solid/liquid interface.Most commonly,heuristic concepts in the realm of materials screening by the compilation of volcano plots are used,which rely on a plethora of simplifications and approximations of the complex electrochemical interface.While the investigation of the catalytic processes at the solid/liquid interface mainly relies on descriptor-based approaches,in the present future article it is discussed that the inclusion of the liquid part of the interface by mean-field models is crucial to elevate screening approaches to the next level.

Derivation and validation of a preoperative prognostic model for resectable pancreatic ductal adenocarcinoma

Background: The prognosis of patients with pancreatic ductal adenocarcinoma(PDAC) remains poor even after radical pancreaticoduodenectomy(PD). The study aimed to develop and validate a novel preoperative prognostic model to accurately predict the long-term survival of patients with PDAC.Methods: Patients with PDAC of pancreatic head from Chinese PLA General Hospital were included. The preoperative PDAC model with contour plots was developed using a non-linear model in the training cohort and then tested in the validation cohort.Results: Of 421 patients who met the inclusion criteria, 280 were in the training cohort and 141 in the validation cohort. Contour plots for preoperative PDAC model were established to visually predict the survival probabilities of these patients, based on preoperative carbohydrate antigen 19-9, preoperative fibrinogen to albumin ratio and pain symptoms. This model stratified patients into low-and high-risk groups with distinctly different long-term survival in the training cohort [median overall survival(OS)32.1 vs. 17.5 months;median recurrence-free survival(RFS) 19.3 vs. 10.0 months, both P < 0.001] and the validation cohort(median OS 28.3 vs. 19.0 months;median RFS 17.5 vs. 11.2 months, both P < 0.001).Time-dependent receiver operating characteristic and decision curve analyses revealed that the model provided higher diagnostic accuracy and superior net benefit compared to other staging systems.Conclusions: This study constructed and validated a novel preoperative prognostic model that can accurately and conveniently predict the long-term survival of patients with resectable PDAC of pancreatic head. Besides, the model can screen high-risk patients with poor prognosis, which may provide references for personal treatment strategies in the future.

Drivers of the differentiation between broad-leaved trees and shrubs in the shift from evergreen to deciduous leaf habit in forests of eastern Asian subtropics

In eastern Asian subtropical forests,leaf habit shifts from evergreen to deciduous broad-leaved woody plants toward higher latitudes.This shift has been largely explained by the greater capacity of deciduous broad-leaved plants to respond to harsh climatic conditions(e.g.,greater seasonality).The advantages of deciduous leaf habit over evergreen leaf habit in more seasonal climates have led us to hypothesize that leaf habits would shift in response to climate changes more conspicuously in forest canopy trees than in forest understory shrubs.Furthermore,we hypothesize that in the forests of the subtropics,plants at higher latitudes,regardless of growth form,would better tolerate seasonal harsh climates,and hence show less differentiation in leaf habit shift,compared to those at lower latitudes.To test these two hypotheses,we modelled the proportion of deciduous broad-leaved species and the incidence of deciduous and evergreen broad-leaved species in woody angiosperm species compositions of ten largesized forest plots distributed in the Chinese subtropics.We found that the rate of leaf habit shift along a latitudinal gradient was higher in forest trees than in forest shrubs.We also found that the differentiation in leaf habit shift between trees and shrubs is greater at lower latitudes(i.e.,warmer climates)than at higher latitudes(i.e.,colder climates).These findings indicate that specialized forest plants are differentially affected by climate in distinct forest strata in a manner dependent on latitudinal distribution.These differences in forest plant response to changes in climate suggest that global climate warming will alter growth forms and geographical distributions and ranges of forests.

Nonlinear dynamics in Divisia monetary aggregates:an application of recurrence quantification analysis

We construct recurrence plots(RPs)and conduct recurrence quantification analysis(RQA)to investigate the dynamic properties of the new Center for Financial Stability(CFS)Divisia monetary aggregates for the United States.In this study,we use the lat-est vintage of Divisia aggregates,maintained within CFS.We use monthly data,from January 1967 to December 2020,which is a sample period that includes the extreme economic events of the 2007–2009 global financial crisis.We then make comparisons between narrow and broad Divisia money measures and find evidence of a nonlinear but reserved possible chaotic explanation of their origin.The application of RPs to broad Divisia monetary aggregates encompasses an additional drift structure around the global financial crisis in 2008.Applying the moving window RQA to the growth rates of narrow and broad Divisia monetary aggregates,we identify periods of changes in data-generating processes and associate such changes to monetary policy regimes and financial innovations that occurred during those times.

乙酰泽泻醇降低胆固醇分子机制研究

目的从分子水平探讨乙酰泽泻醇降低胆固醇(TC)的作用机理。方法利用试剂盒法测定了调脂中药泽泻主要有效成分23-乙酰泽泻醇B和24-乙酰泽泻醇A对高脂小鼠TC的影响,利用试剂盒法、Western blotting技术结合分子模拟技术研究两者对TC代谢关键酶3-羟基-3-甲基戊二酸单酰辅酶A(HMG-Co A)还原酶作用的分子机理。结果乙酰泽泻醇能显著降低高脂小鼠TC(P<0.01,P<0.05),23-乙酰泽泻醇B作用强度高于24-乙酰泽泻醇A(P<0.05),同时在体内、体外均可剂量依赖性下调HMG-Co A还原酶活性(P<0.01),且23-乙酰泽泻醇B对该酶作用强于24-乙酰泽泻醇A(P<0.05)。两者均未显著下调HMG-Co A还原酶的蛋白表达(P>0.05)。两者与HMG-Co A还原酶结合的关键氨基酸残基可能为Lys691、Asp767、Asn658。结论乙酰泽泻醇降低TC的机制可能是其原型药物通过抑制HMG-Co A还原酶活性来达到,且可能是通过直接竞争性与HMG-Co A还原酶结合抑制其作用,乙酰泽泻醇的舵手基团为其侧链,侧链与母环折叠结合弱,打开结合强。

On Reserves of Hippophae rhamnoides L. Fruit on the Territory of the Zarafshan National Nature Park of Uzbekistan

The article is devoted to the study of stocks of Hippophae rhamnoides fruits on the territory of the Zarafshan National Park. Hippophae rhamnoides is a medicinal plant. This species is a naturally distributed plant. All parts of Hippophae rhamnoides are a source of biologically active substances, especially flavonoids, carotenoids, phytosterols and others. In the course of field studies, 10 monitoring sites were selected in the size of 10 × 10 m, and the productivity of one site in the amount of 10 × 10 averaged 51.33 ± 8.24 kg. According to the results obtained, it was revealed that the biological reserve averages 21.9 tons, respectively, the operational reserve is 13.14 tons and the volume of annual harvesting averages 1.31 tons. When the water level of the Zarafshan River rises, some plants are damaged.

Produced Water Geochemistry from an Upstream Oil Operation

Oil and gas industries generate a significant amount of water during the production. The composition of this water varies with the geologic age, depth, and geochemistry of the region along with the chemicals added during the process. Geochemistry of formation water is used for aquifer identification, pollution problems, water compatibility studies, corrosion monitoring, water-quality control, water flooding, exploration, and to diagnose wellbore integrity issues. The current study investigates the spatial and temporal variation of produced water geochemistry from one of the largest conventional oil field, Ghawar field, Saudi Arabia. Produced water from different wellheads were collected and analyzed for different geochemical characteristics. Sixteen wells from ABQQ, nineteen wells from ANDR and twenty wells from SDGM area were selected for the current study. Sampling and analysis were performed as per the standard procedures. Results indicated that the pH of the sample varied from 6.0 to 7.4, and Electrical conductivity from 94200 to 102690 μS/cm. The spatial variation of major cations and anions were also recorded and represented by graphical plots. Metal analysis indicated the highest concentration for boron, which is 20.5 mg/L at ABQQ area, whereas all other metals are very low in concentration. Temporal variation of a single well at SDGM area indicated drastic change in the ionic concentration, whereas the geochemistry remains same as indicated by Tickler plot. The water type of the respective area was studied by tickler plots, which indicated same source of formation water in different wells at ABQQ, ANDR and SDGM areas. The ionic concentration is also used to predict corrosion and scaling issues. By Langelier Saturation Index (LSI) and Ryznar Stability Index (RSI), the sample from all the wells showed higher scaling potential. The study concludes that the water type in different areas under Ghawar field remains same regardless of drastic changes in the ionic concentration, which can be used to diagnose wellbore integrity issues.

华北低丘山区栓皮栎生态系统氧同位素日变化及蒸散定量区分

利用稳定同位素技术对华北低丘山区栓皮栎生态系统氧同位素日变化及蒸散定量区分进行研究,为华北低丘山区森林生态系统水汽交换研究提供基础。试验采用离轴积分腔输出光谱技术(OA-ICOS)连续测定生态系统不同高度水汽浓度和δ18O值,同时采用真空提取和液态水同位素分析仪测定枝条和土壤的δ18O值。结果显示,4个晴天中大气水汽浓度日变化复杂,变化趋势差异大,而δ18O日变化均成高-低-高的"V"型变化,最小值出现在12:00—18:00。Keeling方程在10:00—12:00的相关系数R2均大于0.71,方程达到极显著水平,表明此时段蒸腾速率较高,满足植物蒸腾的同位素稳定态假设。利用Keeling方程估算的栓皮栎生态系统δET值有相似的低-高-低日变化,与大气的δv值变化趋势相反。同位素分割结果显示栓皮栎生态系统中蒸腾占蒸散比例日变化呈现低-高-低的趋势,10:00—14:00蒸腾占蒸散比例达到90%以上,尽管6:00—10:00和14:00—18:00的蒸腾占蒸散比例下降,但平均值仍高达69.38%,表明华北低丘山区栓皮栎生态系统的蒸散主要来源于植物蒸腾。

利用原位连续测定水汽δ^(18)O值和Keeling Plot方法区分麦田蒸散组分

利用稳定同位素技术和Keeling Plot方法可以有效分割地表蒸散量,进而加深对陆地生态系统水循环的理解。该研究通过原位连续测定麦田的水汽同位素数据,评价Keeling Plot方法在分割地表蒸散中的应用,并揭示华北冬小麦(Triticum aes-tivum)蒸腾在总蒸散中的比例。实验于2008年3-5月在中国科学院栾城农业生态站进行,利用国际上先进的H218O、HD16O激光痕量气体分析仪(TDLAS)为基础构建的大气水汽18O/16O和D/H同位素比原位连续观测系统,同时利用涡度相关技术、真空抽提技术、同位素质谱仪技术,获取了必要的数据。研究分析了一天中不同时间段的连续的大气水汽δ18O与水汽浓度倒数拟合Keeling Plot曲线的差异和可能的原因。结果显示,中午时段的拟合结果较好,这也暗示中午时段蒸腾速率高时最可能满足植物蒸腾的同位素稳定态假设。进一步的分析发现植物蒸腾的同位素稳定态并不总是成立,尤其是水分胁迫下进入成熟期的小麦,其蒸腾水汽同位素一般处于非稳定态。利用同位素分割结果显示,生长盛期麦田94%-99%的蒸散来源于植物蒸腾。

毛细管多维气相色谱法分析炼厂气

用ＨＰ６８９０）气相色谱仪，使用多孔层空心毛细管柱（ＰＬＯＴ），选用ＨＰ－ＰＬＯＴ／Ｐｏｒａｐａｃｋ Ｑ色谱柱测定ＣＯ２； ＨＰ－ＰＬＯＴ ５Ａ分子筛柱测定Ｏ２， Ｎ２， ＣＨ４； ＨＰ－ＰＬＯＴ／Ａｌ２Ｏ３柱测定有机烃类。采用３阀４柱色谱运行系统，用ＦＩＤ及ＴＣＤ分别检测烃类及无机气体组分。用色谱工作站控制气动切换阀切换气样走向及两种检测器数据的转换校正和归一化定量计算，用已知物对照法定性，测定了炼厂气中２０余种组分。其准确度和再现性良好。

高效PLOT碳分子筛石英毛细管柱的研制及其性能研究

选用碳分子筛作吸附剂 ,用液相沉淀法涂渍出高效PLOT碳分子筛石英毛细管色谱柱 ,并对其色谱性能进行了考察。结果表明 ,该色谱柱具有良好的分离特性 ,1次进样可分离出O2、N2、CO、CO2、CH4、C2H2、C2H4、C2H6 等组分;适用于炼厂气、烟道气、水煤气及变压器油溶解气等的分析。

小兴安岭红松阔叶混交林土壤动物群落研究

Soil animal communities of Pinus koraiensis broad_leaved mixed forest were studied.The purpose was to discuss the dynamic characteristic of soil animals and relationship with environmental factors.The ecosystem geography distribution law of soil animals, soil animals’role and function in ecological system were revealed.In June,August,October each year,three plots were selected. In each plot, four layers were sampled(litter layer,0～10 cm,10～20 cm & 20～30 cm),adding up to 72 soil sample.The area for large_sized soil animals was 50 cm×50 cm,and the area for middle_small_sized soil animals was 10 cm × 10 cm.Separated soil animals through adopting hand_picking method and Tullgren method respectively.Sampled the soil animals in two continuing years.Shannon_Wiener index was adopted to analyze the diversity of soil animals.Monad liner regression was used to search the relationship between soil animals and environmental factors.The dominant groups were Oribatida, Isotomidae.There were relatively great changes in groups and individual numbers of dominant groups and rare groups when the reason changed.The individual numbers of dominant groups and the groups of rare groups changed.The number of individual and group was the most in August.Obviously it correlated with climatic factors in middle temperate zone.The evenness was low and dominance was high. The diversity index was not most.Among the annual fluctuating there was a increasing trend. The evenness was low and dominance was high.The diversity index was low.It conformed with the law of reason change.The correlation between soil animals and atmospheric temperature,rainfall,ground temperature and sunlight showed the correlation with rainfall and soil temperature was the most significant.

Mathematica在函数作图中的应用

通过介绍Mathematica在函数作图中的应用,为数学教学、数学实验等提供了一个新的适用工具,在多媒体教 学中能直观,形象的描出各种函数的图形,使教学更加深动、形象.