POT Model Research Articles

Migration patterns of phthalic acid esters from mulch plastic film in the soil-plant-atmosphere continuum system

Plastic film mulching is an important agricultural practice, but its release of phthalic acid esters (PAEs) poses threats to soil and human health. However, the migration patterns of PAEs during the lifecycle of mulch plastic film (MPF) remain unclear. This study aims to explore the temporal patterns of release of PAEs during the MPF's lifecycle and evaluate the migration patterns of PAEs from MPF in the soil-plant-atmosphere continuum (SPAC) system through pot experiments and model simulations. The results reveal that during the mulching period, 44.90–56.71 % of the PAEs released went into the atmosphere and 14.97–18.90 % into the soil, while during the residual film period, 24.39–40.13 % were slowly released into the soil. Elevated soil water content increased maize transpiration rates, leading to higher concentrations of PAEs in roots, stems, and fruits, but lower concentrations in leaves. In 2020, the estimated total release of PAEs from MPF in northwest China amounted to 35.42 tons. Notably, PAEs predominantly accumulated in the soil, with minimal accumulation in plant tissues. Moreover, PAEs were primarily removed through degradation. Our results elucidate the migration patterns of PAEs from MPF in the SPAC system, facilitating the evaluation of PAE pathways into the human food chain.

Building Value Assessment and Protection Model under Catastrophe Risk

In recent years, with the change in the global environment, the frequency of catastrophes has been increasing, which poses a great threat to people's property and life safety. Many landmark buildings have high historical or economic value, and it is important to assess the value of these buildings and develop conservation plans. To evaluate the value of the building, this article first established the POT model to evaluate the risk of the building location. Then, based on the EWM-AHP method, we selected the first-level indicators and the second-level indicators to establish the value evaluation model of the building and used the logic function to establish the protection model through data fitting. According to the comprehensive analysis of the risk assessment and the value assessment of the building, the building protection measures are divided into three types: unprotected, reinforced, and relocated. It is applied to the church of San Marco in Venice, and it is concluded that the area needs to be reinforced. The establishment of the model is of great significance to the evaluation and protection of buildings.

Penerapan Teknologi Augmented Reality Catalog Digital Pot Bunga Berbasis Android

Home industry or is known home industry has many variations, one of which is flower pot, as a storage medium for plants, flower pot can also be used as decorations to beautify plants, flower pot sellers are now in great demand in Candiharjo residents. Candiharjo residents started to develop a business selling flower pot because the way to make them is very easy and has a lot of devotees. The background of interest in this research is based on the results of observations made with home industry sellers. In general, services for ordering or marketing media use brochures using photos without being able to explore in more detail, therefore a new service is needed so that they can display products in real time in 3 dimensions (3D) and can be interactive with buyers. The author's goal of conducting this research is to design an application so that Flower Pot buyers are interested in the products offered by sellers through digital catalogs using Augmented Reality (AR) technology and make it easier for buyers to visualize Flower Pot models interactively. The results of this study are the Augmented Reality Digital Catalog Application to provide an interactive visualization of the Flower Pot model in 3 dimensions using a 3D developer application.

Development And Filtration Performance of Ceramic Filters from Ikot Ebom Clay

This research used the hand impress moulding method to prepare ceramic filter pots using 500 μm sieved clay, grog, and melon shell in three ratios of 70:5:25, 75:5:20, and 80:5:15, respectively. The pot models were dimensioned to 50 mm height, 52 mm outer diameter, and 10 mm thickness and fired to 650°C, 700°C, and 750°C. The volume of effluent, flow rate, and microbial removal efficiency were studied. From the results, filter pot 70:5:25 fired to 750°C recorded an efficiency of 99.9% removal of heterogenic bacteria count, total fungi count, total coliform, and E.coli, and has the best combination of flow rate and removal efficiency. This filter pot was seen to meet up with World Health Organization (WHO) standards. Minitab analyses show a significant effect of material composition over fired temperature on the flow rate.Keywords: Water filtration, porosity, ceramic, filter pot

Pricing Multi-Event-Triggered Catastrophe Bonds Based on a Copula–POT Model

The constantly expanding losses caused by frequent natural disasters pose many challenges to the traditional catastrophe insurance market. The purpose of this paper is to develop an innovative and systemic trigger mechanism for pricing catastrophic bonds triggered by multiple events with an extreme dependence structure. Due to the bond’s low cashflow contingencies and the CAT bond’s high return, the multiple-event CAT bond may successfully transfer the catastrophe risk to the huge financial markets to meet the diversification of capital allocations for most potential investors. The designed hybrid trigger mechanism helps reduce the moral hazard and increase the bond’s attractiveness with a lower trigger likelihood, displaying the determinants of the wiped-off coupon and principal by both the magnitude and intensity of the natural disaster events involved. As the trigger indicators resulting from the potential catastrophic disaster might be associated with heavy-tailed margins, nested Archimedean copulas are introduced with marginal distributions modeled by a POT-GP distribution for excess data and common parametric models for moderate risks. To illustrate our theoretical pricing framework, we conduct an empirical analysis of pricing a three-event rainstorm CAT bond based on the resulting losses due to rainstorms in China during 2006–2020. Monte Carlo simulations are carried out to analyze the sensitivity of the rainstorm CAT bond price in trigger attachment levels, maturity date, catastrophe intensity, and numbers of trigger indicators.

Research on Aero-engine Maneuvering Load Distribution Based on POT Model

Research on Aero-engine Maneuvering Load Distribution Based on POT Model

Forecasting extreme negative returns in gold and silver: A discrete‐duration approach to POT models

AbstractSudden and massive drops in precious metal prices severely impact the investment risk on these commodity markets. In this study, we examine the dynamics of extreme negative returns on gold and silver, as well as propose the discrete‐duration version of the autoregressive conditional duration peaks‐over‐threshold (ACD‐POT) model for measuring market risk. The model is tailored for the dynamics of extreme events in precious metal markets; this is because it can exhibit both the strong clustering of extreme‐event days, and the serial correlation in the magnitudes of extreme losses. From an econometric perspective, our approach complements the existing dynamic versions of POT models; this is so that the time interval (i.e., duration) between the extreme negative returns is treated not as a continuous variable, but as a discrete one. The discrete hazard function in our model represents the daily extreme loss event probability and it can be used to derive one‐day‐ahead forecasts of both the value at risk and expected shortfall for investments in gold and silver. Formal backtesting methods show that the discretized version of the POT model has a superior in‐sample fit and forecasting performance than the continuous‐duration POT models.

The Unfinished Business of Unsettled Things: Art from an African American South

The Unfinished Business of Unsettled Things: Art from an African American South

Compilation and Extrapolation of Load Spectrum of Tractor Ground Vibration Load Based on CEEMDAN-POT Model

Effective indoor testing on a four-poster rig of agricultural machinery should mimic the real-world environment while the machinery is in farming and transportation. The emerging load spectrum extrapolation and compilation are capable of speeding up the use of the indoor vibration testing of tractors. However, most ground load spectrum studies consider a particular type of ground rather than all the rough farmland conditions that tractors experience daily. Such a problem inevitably raises doubts about validating the load spectrum-based fatigue durability and reliability testing of tractors. For a remedy, this article proposes a CEEMDAN-POT (Peak Over Threshold) model to comprehensively build a full life-cycle ground load spectrum of tractor vibration with six ground conditions and different field operations. The study acquires the real four vertical acceleration signals from the front and rear axles of the tractor to collect representative vibration load data. Furthermore, the study refines the measured load data by proposing a CEEMDAN-Wavelet threshold method, which is proved to be effective for the load signal decomposition and denoising. Lastly, the study presents a time domain extrapolation method, integrating the sample principle of the POT model, the proper parameter estimation with the Generalized Pareto Distribution (GPD) function, and the POT super-threshold model. The statistical analysis implies that the produced load spectrum fully preserves the statistical features observed in the original one. After extrapolation, the overall distribution of the rainflow matrix becomes more consistent while the mean and amplitude of the spectrum data increase. This study unifies a load spectrum of tractors operating and transporting on various farm ground conditions, providing the real load data of the indoor four-poster rig test.

油葵穴盘苗钵体离散元参数标定与试验验证

The movement of plug seedlings and the pots damage mechanism are deeply studied during the planting process, and the planting components are optimized. The Tekscan pressure distribution measurement system was used to measure the mechanical characteristics of the drop impact between the whole plug seedlings and the pots. The relative error between the collision impact force of the plug seedlings and the collision impact force of the pot is less than 20%. Therefore, a drop impact test using the pot allows the whole plug seedling to be characterized. The Hertz-Mindlin with bonding model was used to build a simulation model of the pot based on essential physical parameters. The Plackett-Burman test and the steepest climbing test determined the significant parameters and optimal intervals affecting the collision impact force: the rolling friction coefficient between the pot and pot was 0.35~0.38, the bond stiffness was 0.2~0.6 MN·m-3, and the bond radius was 1.56~1.98 mm. Finally, the Box-Behnken test was performed and the quadratic regression model of the collision impact force was developed. Taking the collision impact force with a drop height of 350 mm as the target, the optimal solution is obtained: the rolling friction coefficient between the pot and pot was 0.35, the bond stiffness was 0.53 MN·m-3, and bond radius 1.97 mm. The average value was used for other insignificant influence parameters. The simulation results are compared with the physical test, and the relative error is 3.65%. Therefore, the pot model established by this simulation parameter can represent the actual drop impact of the pots.

Quadratic Bezier Curve as the base for pot modelling

Pot is a place or container made of clay, earthenware, cement, or plastic to plant trees or plants. In addition to a place to plant plants, pots also function to decorate the appearance of the house, both on the outside (outdoor) or in the room (indoor). So that the selection of the right pot model can make the yard or corner of the room look more comfortable, beautiful, and attractive. Some pot models that are already on the market have a circular or rectangular base with a monotonous pot shape. Thus, the researcher conducted on the pot modelling with the initial data of regular hexagon polygons as the base of the pot and the Quadratic Bezier curve as the basis for modelling pots with the help of Maple software. This research method uses applied research methods, namely the application of the Quadratic Bezier Curve in making pot models, several pot models were produced, namely a pot with two tiers and three tiers, where each level has several potted models with twisted and symmetrical types. So that the pot models obtained are more attractive and have artistic value.

Research on Financial Market Risks Based on VaR Model

With the continuous development of the Internet financial industry, its impact on people's daily life is growing. Under the influence of the information technology and the financial innovation, the volatility of the financial market has been significantly enhanced, and the financial risk has become increasingly serious. The COVID-19 in 2020 still has a profound impact on the global financial market. The reasonable measurement of the financial risks is the most important step in the financial risk management. Based on the sample analysis of the Standard & Poor's 500 Index from January 3, 2013 to June 30, 2020, this paper measures the risks by analyzing and calculating the value at risk (VaR) of the sample data by different methods. This paper mainly establishes the ARMA model, the GARCH model based on bayese statistics, and the POT model based on the extreme value theory, and compares and analyzes the VaR values obtained by the three models. Finally, the effectiveness of VaR is tested by VaR backtracking test, and the advantages and disadvantages of the methods are compared and evaluated.

Production efficiency in handicrafts manufacturing on the example of decorative ceramics: the use of training for making craft products made of glass fiber reinforced concrete

This study aims to determine the benefits of training in making decorative pots with GFRC material to increase production time efficiency. The glass fiber reinforced concrete (GFRC) is a material technology in the manufacture of handicrafts using a mixture of cement, milk, and glass fiber. Training to make handicrafts from GFRC material is one alternative to increase the efficiency of ornamental pot products. This study used the descriptive qualitative method. The research was carried out in a special area of Yogyakarta by involving 20 members of the Indonesian Furniture and Handicraft Industry Association (ASMINDO) Yogyakarta. Data were obtained by direct observation of the training activities carried out. The data were analyzed using the Miles and Huberman model, namely data reduction, tabulation, data presentation, and concluding. The results showed that the training was carried out by considering the curriculum, training materials and methods, experimental processes, and production efficiency. Participants were able to make four new pot models according to the trend of craft product design. New models and manufacturing methods can be used as a reference to produce shapes and finishes. The participants felt the benefits and applied this technique in the craft production process. Therefore, the effectiveness of productivity and the economy and welfare can be increased in MSMEs in Yogyakarta.

Time-domain extrapolation method for tractor drive shaft loads in stationary operating conditions

The fatigue failure of critical parts of tractors over the whole life cycle has received much attention in recent years. Load extrapolation is a crucial step in load spectrum compilation and can extrapolate the product's life cycle load based on limited load data measurements. The traditional time-domain extrapolation method is limited because it neglects the time interval between the load changes and the load reconstruction within the threshold range. To address this problem, a time-domain extrapolation method for tractor drive shaft load based on the Markov chain Monte Carlo-peak over threshold (MCMC-POT) model is proposed. Firstly, an improved time-domain load reconstruction method based on MCMC that can reproduce the load change interval based on the measured load change characteristics was proposed. Secondly, in the POT model extrapolation process, an improved threshold selection algorithm that is an optimisation of the traditional mean excess function (MEF) method was proposed. This method avoids the errors caused by subjective factors under the premise of ensuring the fitting accuracy. Finally, the dynamic torque spectrum was obtained by extrapolating the tractor drive shaft load data measured under ploughing conditions. Case analysis results showed that the method can obtain extrapolation models with high fitting accuracy. The power spectral density values of the dynamic torque spectrum before and after extrapolation were very consistent with the mean correlation coefficient of 0.909. The spectrum can effectively reproduce the time-frequency characteristics of the load. Furthermore, the precision of the load spectrum is improved. • A time-domain load reconstruction method based on Markov chain Monte Carlo model. • The threshold selection method based on peak over threshold model was improved. • A load extrapolation method that can retain complete time-frequency information. • Tractor transmission shaft testing was implemented under ploughing conditions. • The extrapolated load has the consistent frequency spectrum with the measured.

Rethinking Assessment in EFL Writing: The Melting Pot Model

Rethinking Assessment in EFL Writing: The Melting Pot Model

The Influence of Stock Liquidity on Tail Risk of Stock Market: An Empirical Research Based on POT Model

The Influence of Stock Liquidity on Tail Risk of Stock Market: An Empirical Research Based on POT Model

Prediction Research and Application of Financial Time Series Based on Big Data

Financial risk is conductive in the market. In this paper, correlation function is used to model the relevant structure of the financial market. The j-B test statistic value of four stocks is far greater than the critical value of 6.7325, and the critical value of LJung-Box-Pierce test is 32.1342. At the same time, it is proved that the selection of edge distribution function is independent of the dependent structure, but the risk value estimated by semi-parametric POT model is higher than that estimated by kernel density function.

University practitioners’ critical reflections from the collaboritive model

This investigation aimed to report University practitioners' critical reflections generated from Gosling's third POT model to raise awareness of institutional authorities and educationalists on the importance of consolidating POT programs on a regular basis. This qualitative case study was conducted with a sample of fourteen instructors currently working in a Public University situated in the Ecuadorian highlands. This group of academic practitioners was divided into pairs so that seven subgroups resulted from this division. Each subgroup worked firstly on the collaborative model process, which contemplated observation forms; then, they executed critical reflections; this data was gathered in collaborative expository essays and encapsulated in this manuscript. The obtained results disclose a high proclivity towards ongoing professional development, said differently; there is a considerable desire on the part of our participants to cultivate a teaching evaluation philosophy on a rolling basis. In general, this study had a positive repercussion on those involved due to its substantial interchangeable reflections.

A method of determining monitoring indexes for spatial deformation of super high arch dam based on extreme value theory

In the long service of arch dam, deformation is one of the main performance parameters which can directly reflect the working behavior of the dam. In order to effectively monitor the safety of dam operation, it is necessary to determine the monitoring control value of deformation. The traditional dam deformation monitoring control values only consider the single point, ignoring the spatial correlation between the measurement points. In order to overcome this limitation, this paper focuses on the spatial distribution characteristics of deformation measuring points of the arch dam, then by building dam deformation field and using the Projection Pursuit Analysis (PPA) project high-dimensional data to low dimensional space. On this basis, the POT model proposed to determine the monitoring control values. The PPA-POT model is applied to practical engineering, and the feasibility and applicability of the method in this paper are tested by comparing with the traditional methods, so as to provide a new analysis technique for the long-term service status safety evaluation of arch dams.

A Mahalanobis Distance‐Based Automatic Threshold Selection Method for Peaks Over Threshold Model

AbstractAn unresolved problem in statistical analysis of hydrological extremes (e.g., storms, floods) using POT model is identification of optimal threshold. There are various issues affecting performance of different methods available for threshold selection (TS). To overcome those issues, this study contributes a novel Mahalanobis distance‐based automatic TS method. It involves use of proposed transformation to map Generalized Pareto distributed random variable (depicting peaks over tentative thresholds) from the original space to standard exponential (Exp(1)) distributed random variable in a nondimensional space. Optimal threshold is identified as that which minimizes Mahalanobis distance between L‐moments of the transformed random variable and those of the population (i.e., Exp(1) distribution) in the nondimensional space. Its effectiveness is demonstrated over four existing automatic TS methods through Monte Carlo simulation experiments and case studies over rainfall and streamflow data sets chosen from India, United Kingdom, and Australia. The four methods include three based on goodness of fit (GoF) test statistics (of Anderson‐Darling and two nonparametric tests), and a recent one based on L‐moment ratio diagram whose potential is unexplored in hydrology. This study further provides insight into properties and effectiveness of the four TS methods, which is scanty in literature. Results indicate that there is inconsistency in performance of GoF test‐based methods across data sets exhibiting fat and thin tail behavior, owing to their theoretical assumptions and uncertainty associated with sampling distribution of test statistics. Issues affecting performance of L‐moment ratio diagram‐based TS method are also identified. The proposed method overcomes those issues and appears promising for hydrologic applications.