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Operating Room Time Prediction: An Application of Latent Class Analysis and Machine Learning 手术室时间预测:潜在类分析和机器学习的应用
Q4 Engineering Pub Date : 2021-11-02 DOI: 10.11144/javeriana.iyu26.ortp
Eduard Gañan-Cardenas, Jorge Isaac Pemberthy-Ruiz, Juan Carlos Rivera-Agudelo, Maria Clara Mendoza- Arango
Objective: The objective of this work is to build a prediction model for Operating Room Time (ORT) to be used in an intelligent scheduling system. This prediction is a complex exercise due to its high variability and multiple influential variables. Materials and methods: We assessed a new strategy using Latent Class Analysis (LCA) and clustering methods to identify subgroups of procedures and surgeries that are combined with prediction models to improve ORT estimates. Three tree-based models are assessed, Classification and Regression Trees (CART), Conditional Random Forest (CFOREST) and Gradient Boosting Machine (GBM), under two scenarios: (i) basic dataset of predictors and (ii) complete dataset with binary procedures. To evaluate the model, we use a test dataset and a training dataset to tune parameters. Results and discussion: The best results are obtained with GBM model using the complete dataset and the grouping variables, with an operational accuracy of 57.3% in the test set. Conclusion: The results indicate the GBM model outperforms other models and it improves with the inclusion of the procedures as binary variables and the addition of the grouping variables obtained with LCA and hierarchical clustering that perform the identification of homogeneous groups of procedures and surgeries.
目的:建立用于智能调度系统的手术室时间(ORT)预测模型。由于其高变异性和多个影响变量,这种预测是一项复杂的工作。材料和方法:我们评估了一种新的策略,使用潜在分类分析(LCA)和聚类方法来确定手术和手术的亚组,并结合预测模型来提高ORT估计。在两种情况下,对分类与回归树(CART)、条件随机森林(CFOREST)和梯度增强机(GBM)三种基于树的模型进行了评估:(i)预测者的基本数据集和(ii)具有二值过程的完整数据集。为了评估模型,我们使用测试数据集和训练数据集来调整参数。结果与讨论:使用完整数据集和分组变量的GBM模型获得了最好的结果,在测试集中的操作准确率为57.3%。结论:结果表明,GBM模型优于其他模型,并随着将手术作为二元变量,以及加入LCA和分层聚类获得的分组变量,对手术和手术的同质组进行识别而得到改进。
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引用次数: 0
IDC Sensor for Low-Cost Water Quality Monitoring Applications 用于低成本水质监测的IDC传感器
Q4 Engineering Pub Date : 2021-11-02 DOI: 10.11144/javeriana.iyu26.islc
Diego Mendez-Chaves, Manuel Perez, Alejandro Farfan, E. Gerlein
In order to properly monitor the health status of the hydrological resources of a region, in terms of water contamination, a scalable and low-cost system is necessary to map the water quality at different locations and allow the prioritization of more sophisticated and expensive monitoring campaigns on those areas where a suspicious behavior seems to be occurring. This paper presents the design and implementation process of such an IoT-based solution for low-cost and scalable water quality monitoring applications. To achieve that end, we propose the utilization of a low-cost inter-digital capacitance (IDC) sensor to characterize the conductivity of the water, a very telling parameter about the level of pollution in the water. Additionally, an embedded method to measure such sensor was designed and implemented, which considers the requirements of a portable platform: low computational capabilities, small memory and low power consumption. Our results show that an IDC sensor is capable of detecting the changes of the capacitance of the sample, and therefore mapping the changes in the conductivity of the water. Additionally, integrating an embedded measuring method is a valid option for in-situ characterization of water samples and the complete solution enables a new paradigm for water quality monitoring in large scale scenarios.
为了适当地监测一个地区水文资源的健康状况,就水污染而言,需要一个可扩展和低成本的系统来绘制不同地点的水质图,并允许在可疑行为似乎正在发生的地区优先进行更复杂和昂贵的监测活动。本文介绍了这种基于物联网的解决方案的设计和实现过程,用于低成本和可扩展的水质监测应用。为了实现这一目标,我们建议利用低成本的数字间电容(IDC)传感器来表征水的电导率,这是关于水中污染水平的一个非常有意义的参数。此外,设计并实现了一种嵌入式测量方法,该方法考虑了便携式平台的要求:低计算能力、小内存和低功耗。我们的研究结果表明,IDC传感器能够检测样品的电容变化,从而绘制水的电导率变化。此外,集成嵌入式测量方法是对水样进行原位表征的有效选择,完整的解决方案为大规模场景中的水质监测提供了新的范例。
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引用次数: 0
Optimization of Machining Parameters for Product Quality and Productivity in Turning Process of Aluminum 铝车削加工参数优化对产品质量和生产率的影响
Q4 Engineering Pub Date : 2021-10-13 DOI: 10.11144/javeriana.iued26.ompp
Sepideh Abolghasem, Nicolás Mancilla-Cubides
Modern production process is accompanied with new challenges in reducing the environmental impacts related to machining processes. The turning process is a manufacturing process widely used with numerous applications for creating engineering components. Accordingly, many studies have been conducted in order to optimize the machining parameters and facilitate the decision-making process. This work aims to optimize the quality of the machined products (surface finish) and the productivity rate of the turning manufacturing process. To do so, we use Aluminum as the material test to perform the turning process with cutting speed, feed rate, depth of cut, and nose radius of the cutting tool as our design factors. Product quality is quantified using surface roughness (R_a) and the productivity rate based on material removal rate (MRR). We develop a predictive and optimization model by coupling Artificial Neural Networks (ANN) and the Particle Swarm Optimization (PSO) multi-function optimization technique, as an alternative to predict the model response (R_a) first and then search for the optimal value of turning parameters to minimize the surface roughness (R_a) and maximize the material removal rate (MRR). The results obtained by the proposed models indicate good match between the predicted and experimental values proving that the proposed ANN model is capable to predict the surface roughness accurately. The optimization model PSO has provided a Pareto Front for the optimal solution determining the best machining parameters for minimum R_a and maximum MRR. The results from this study offer application in the real industry where the selection of optimal machining parameters helps to manage two conflicting objectives, which eventually facilitate the decision-making process of machined products.
现代生产过程在减少机械加工过程对环境的影响方面提出了新的挑战。车削加工是一种广泛应用于制造工程部件的制造工艺。因此,为了优化加工参数,方便决策过程,进行了大量的研究。本工作旨在优化加工产品的质量(表面光洁度)和车削制造过程的生产率。为此,我们使用铝作为材料测试,以切削速度,进给量,切削深度和刀具的刀尖半径作为我们的设计因素来执行车削过程。用表面粗糙度(R_a)和基于材料去除率(MRR)的生产率来量化产品质量。将人工神经网络(ANN)和粒子群优化(PSO)多功能优化技术相结合,建立了预测和优化模型,首先预测模型响应(R_a),然后搜索车削参数的最优值,以最小化表面粗糙度(R_a)和最大化材料去除率(MRR)。模型的预测值与实验值吻合较好,证明了所提出的人工神经网络模型能够准确预测表面粗糙度。该优化模型为确定最小R_a和最大MRR的最佳加工参数的最优解提供了Pareto Front。本研究的结果在实际工业中具有应用价值,其中最优加工参数的选择有助于管理两个相互冲突的目标,最终促进加工产品的决策过程。
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引用次数: 1
Biofilms Production from Avocado Waste 利用鳄梨废弃物生产生物膜
Q4 Engineering Pub Date : 2021-10-12 DOI: 10.11144/javeriana.iued25.bpaw
H. Sánchez, Wilmer Ponce, B. Brito, W. Viera, R. Baquerizo, M. Riera
Objective: To obtain biofilms from starch and cellulose present in the avocado (Persea americana) peel and seed. Materials and methods: The starch characterization included humidity, gelatinization temperature, paste clarity, absorption index, solubility index, swelling power, amylose, amylopectin, amount, and starch yield. Five mixtures were made with 3 g of starch, 5 mL of 30 % NaOH (w/v), 3 g of cellulose, and different proportions for glycerin: 2 g; 2.5 g; 3 g; 3.5 g; 4 g, and PVA: 2 g, 3 g, 4 g, 5 g, and 6 g. Films were formed on acrylic plates, using the casting method. The bioplastic was characterized in terms of moisture, solubility in water, density, thickness, biodegradability, stress, deformation, and modulus of elasticity. Results and discusión: The addition of cellulose to the mixture does not contribute to film formation, unlike PVA which did. The film had the best physical appearance with a mixture of 2 g of glycerin and 6 g of PVA. The bioplastic characterization was 23.43 % humidity, 39.39 % for water solubility, 1.52 g/cm3 density, 0.58 mm thickness, 21.03 % weight loss for the biodegradability test, 1.53 MPa for tension, 21.25 % deformation, and 10,04 MPa for the modulus of elasticity. Conclusions: The bioplastic obtained did not show the resistance of traditional plastic. However, the results obtained serve as a starting point for the realization of other formulations, aimed at producing a bioplastic capable of competing with its synthetic relatives.
目的:从鳄梨(Persea americana)果皮和种子中的淀粉和纤维素中获得生物膜。材料与方法:淀粉的表征包括湿度、糊化温度、糊状清晰度、吸收指数、溶解度指数、膨胀力、直链淀粉、支链淀粉、用量、淀粉得率。用3g淀粉、5ml 30% NaOH (w/v)、3g纤维素和不同比例的甘油配制成5种混合物:2g;2.5克;3 g;3.5克;4克,聚乙烯醇:2克,3克,4克,5克,6克。薄膜是用铸造法在丙烯酸板上形成的。生物塑料在水分、水中溶解度、密度、厚度、生物降解性、应力、变形和弹性模量方面进行了表征。结果和discusión:在混合物中加入纤维素不会形成薄膜,不像PVA那样。当2 g甘油和6 g聚乙烯醇混合时,膜的物理外观最佳。生物塑性表征为湿度23.43%,水溶性39.39%,密度1.52 g/cm3,厚度0.58 mm,生物降解试验失重21.03%,张力1.53 MPa,变形21.25%,弹性模量10.04 MPa。结论:制备的生物塑料不具有传统塑料的耐药性。然而,所获得的结果可以作为实现其他配方的起点,旨在生产能够与其合成亲戚竞争的生物塑料。
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引用次数: 0
Real-time Coordinated Scheduling for Cloud Radio Access Networks in a Software-only Environment using the OpenAirInterface Platform 基于OpenAirInterface平台的纯软件环境下云无线接入网的实时协调调度
Q4 Engineering Pub Date : 2021-10-12 DOI: 10.11144/javeriana.iued25.rcsc
Luis Felipe Ariza-Vesga, Johan Sebastian Eslava-Garzon
The objective of this paper is to extend into the OpenAirInterface platform the Coordinated Scheduling (CS) technique to allocate resource blocks among User Equipment (UE) in a wisely way and to control the energy efficiency, the throughput, and the inter-cell interference for Cloud Radio Access Networks (C-RANs). It is achieved by modifying the OpenAirInterface scheduler code, increasing the Remote Radio Unit (RRU) scalability, and employing some component carriers of the Radio Cloud Center (RCC), each one them with one or more UEs. The hardware utilized is composed of general-purpose processors and fast Ethernet transport ports, and the software is recent frequency-domain methodologies in a software-only environment where the use of radio units are not required. However, the USRP B200 mini-i radio unit and the UE (Samsung Galaxy S8) were considered only for validation purposes. The emulations using frequency-domain methodologies, compatible with fourth and fifth-generation cellular systems, allowed real-time emulations and reduced 10-fold the multipath channel’s signal processing complexity compared to time-domain methodologies. The results show we can emulate a real-time static coordinated scheduling proof-of-concept for one C-RAN composed of one RCC, three RRUs, and three UEs. In the end, it is evaluated the reproducibility and the scalability of synthetic networks composed of one RRU and at least one UE, without using software-defined radio units, reducing prototyping uncertainties of the physical hardware and the total price of the experiment.
本文的目标是将协调调度(CS)技术扩展到OpenAirInterface平台,以明智的方式在用户设备(UE)之间分配资源块,并控制云无线接入网(c - ran)的能效、吞吐量和小区间干扰。它是通过修改OpenAirInterface调度器代码,增加远程无线电单元(RRU)的可扩展性,并采用无线电云中心(RCC)的一些组件载波来实现的,每个组件载波都有一个或多个ue。所使用的硬件由通用处理器和快速以太网传输端口组成,软件是在不需要使用无线电单元的纯软件环境中使用的最新频域方法。然而,USRP B200 mini-i无线电装置和UE(三星Galaxy S8)仅用于验证目的。仿真使用的频域方法与第四代和第五代蜂窝系统兼容,允许实时仿真,与时域方法相比,将多径信道的信号处理复杂性降低了10倍。结果表明,我们可以模拟一个由一个RCC、三个rru和三个ue组成的C-RAN的实时静态协调调度概念验证。最后,在不使用软件定义无线电单元的情况下,评估了由一个RRU和至少一个UE组成的合成网络的可重复性和可扩展性,减少了物理硬件的原型不确定性和实验的总价格。
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引用次数: 0
Reported Lead Levels in Different Environmental Matrices in Colombia 哥伦比亚不同环境基质的铅含量报告
Q4 Engineering Pub Date : 2021-06-22 DOI: 10.11144/javeriana.iued25.rlld
Carol Brigitte Hernández Rodríguez, A. Gutierrez-Malaxechebarria, Carlos Alfonso Zafra Mejía
Objective: The aim of this paper is to present a review of specific cases that reported lead concentrations in blood, objects, food, soil, bioindicators, air, and water in specific places in Colombia and evaluate the reported concentrations against target values. Materials and Methods: A systematic qualitative literature review of publications between 1995 and 2019 was done; using Boolean operators 1571 papers were identified, to which 3 inclusion and 4 exclusion criteria were applied. A total of 57 studies met the defined criteria. The reports in these studies were geo-localized and compared with acceptable values. Results and Discussion: Results suggest that lead is present in all environmental matrices, widely distributed in the Colombian territory, and that 72 % of the cases exceeded regulation limits. The percentage of noncompliance per environmental matrix was 89 % for blood samples, 71 % in food, 63 %, in soil, 89 % for bioindicators, 60 % for air, and 55 % for water. Conclusion: These results show that lead pollution is a large-scale problem in the country, more systematic studies are needed, and control measures, policy-making and regulatory updating should be pursued.
目的:本文的目的是对哥伦比亚特定地区报告的血液、物体、食物、土壤、生物指标、空气和水中铅浓度的具体病例进行审查,并根据目标值对报告的浓度进行评估。材料和方法:对1995年至2019年的出版物进行了系统的定性文献综述;使用布尔运算符确定了1571篇论文,其中应用了3个纳入标准和4个排除标准。总共有57项研究符合规定的标准。这些研究中的报告是地理定位的,并与可接受的值进行比较。结果和讨论:结果表明,铅存在于所有环境基质中,广泛分布在哥伦比亚境内,72%的病例超过了规定限值。每个环境基质的不合格率在血液样本中为89%,在食品中为71%,在土壤中为63%,在生物指示剂中为89%,在空气中为60%,在水中为55%。结论:我国铅污染是一个大规模的问题,需要进行更系统的研究,并采取控制措施、制定政策和更新法规。
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引用次数: 0
Resources Allocation in Service Planning Using Discrete-Event Simulation 基于离散事件仿真的服务规划资源分配
Q4 Engineering Pub Date : 2021-06-17 DOI: 10.11144/javeriana.iued25.rasp
M. Becerra-Fernández, Milton M. Herrera, C. Trejos, O. R. Romero
Objective: Calculate the required personnel and resources needed to fulfill the service promise agreed with the customer. Methods and materials: This paper presents a discrete event simulation (DES) model developed to select and implement a Point of Sale (POS) for a company providing financial products. First, the paper shows the characterization of the system components and times per process. Then, hypothesis testing and goodness-of-fit statistics are estimated. Subsequently, the simulation scenarios assess the times between arrivals and the number of commercial advisers. Results and discussion: This model allows us to assess the allocation of resources to fulfill the service promise, which is that 80 % of customers must be served within one hour or less. This paper provided the service isoquants allowing us to observe the behavior of the performance metrics (service promise fulfillment) among different scenarios. Conclusions: The use of DES techniques allows for the evaluation of the assignment of personnel to achieve the fulfillment of the service promise, including facilities, equipment, and the evaluation of related processes. These methods can be extended to the analysis of resource allocation in the development of other processes, observing the relationship between service quality and operating costs.
目的:计算完成与顾客约定的服务承诺所需的人员和资源。方法和材料:本文提出了一个离散事件模拟(DES)模型,用于为提供金融产品的公司选择和实施销售点(POS)。首先,本文展示了系统组件的特性和每个过程的时间。然后进行假设检验和拟合优度统计估计。随后,模拟情景评估到达的时间间隔和商业顾问的数量。结果和讨论:该模型允许我们评估资源的分配,以实现服务承诺,即80%的客户必须在一小时或更短的时间内得到服务。本文提供了服务等量,使我们能够在不同的场景中观察性能度量(服务承诺实现)的行为。结论:使用DES技术可以对人员分配进行评估,以实现服务承诺的履行,包括设施,设备和相关过程的评估。这些方法可以扩展到分析其他流程开发中的资源分配,观察服务质量与运营成本之间的关系。
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引用次数: 3
Design of a CPFR, Location, Inventory and Routing Approach to Diabetes and High Blood Pressure Medicine Supply Network Planning 糖尿病和高血压药物供应网络规划的CPFR、位置、库存和路径方法设计
Q4 Engineering Pub Date : 2021-06-17 DOI: 10.11144/javeriana.iued25.dcli
Francisco Andrés Chuchoque-Urbina, Martha Patricia Caro-Gutiérrez, Carlos Eduardor Montoya-Casas
Objective: Designing a CPFR (collaborative planning forecasting and replenishment) model for the delivery of diabetes and arterial hypertension medicines from a health insurance company (EPS) to a healthcare provider (IPS) and comparing the performance of this collaborative chain to that of the traditional one through their corresponding supply chain costs. Methodology: A series of collaboration agreements involved in joint planning were established according to the designed CPFR model. This allowed (i) raising the levels of interaction between the health insurance company, the healthcare provider, the supplying pharmaceutical laboratories, and the patients; (ii) determining demand forecasts; (iii) locating distribution centers; and (iv) defining medicine distribution strategies oriented to the minimization of costs along the chain. Subsequently, the main differences between the current operation and CPFR models at the level of structure and decisions were characterized and then evaluated in terms of supply chain costs. Results: The significant impact of the proposed model is demonstrated. The total monthly cost of operating the chain is reduced by 11.2 % on average. Within the proposed innovation, an outstanding place is held by the savings reached in the purchase and distribution of medicines from the laboratory to the distribution centers, and by the customer satisfaction differences, which increased 15.3 % on average during the studied six-month period.
目的:设计健康保险公司(EPS)向医疗服务提供者(IPS)提供糖尿病和高血压药物的CPFR(协同规划预测和补给)模型,并通过相应的供应链成本比较该协同链与传统协同链的绩效。方法:根据设计的CPFR模型,建立一系列涉及联合规划的合作协议。这使得(i)提高了健康保险公司、医疗保健提供者、提供药品的实验室和患者之间的互动水平;(ii)确定需求预测;(三)设立配送中心;(4)制定以供应链成本最小化为导向的药品配送策略。随后,对当前运营模式和CPFR模式在结构和决策层面的主要差异进行了表征,然后根据供应链成本进行了评估。结果:所提出的模型具有显著的影响。经营连锁店的每月总成本平均降低了11.2%。在拟议的创新中,从实验室到配送中心的药品采购和配送所节省的费用以及客户满意度的差异占据了突出的位置,在研究的六个月期间,客户满意度的差异平均增加了15.3%。
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引用次数: 0
Support Vector Machines Used for the Prediction of the Structural Conditions of Pipes in Bogota’s Sewer System 支持向量机用于波哥大下水道系统管道结构状况的预测
Q4 Engineering Pub Date : 2021-06-17 DOI: 10.11144/javeriana.iued25.svmu
Nathalie Hernández, N. Caradot, H. Sonnenberg, P. Rouault, A. Torres
Objective: this paper focused on: (i) developing a deterioration model based on support vector machines (SVM) from its regression approach to separate the prediction of the structural condition of sewer pipes from a classification by grades and predict the scores obtained by failures found in CCTV inspections; and (ii) comparing the prediction results of the proposed model with the ones obtained by a deterioration model based on SVM classification tasks to explore the advantages and disadvantages of their predictions from different perspectives. Materials and methods: The sewer network of Bogota was the case study for this work in which a dataset consisting of the characteristics of 5031 pipes inspected by CCTV (obtained by GIS) was considered, as well as information on external variables (e.g., age, sewerage, and road type). Probability density functions (PDF) were used to convert the scores given by failures found in CCTV into structural grades. In addition, three techniques were used to evaluate the predictions from different perspectives: positive likelihood rate (PLR), performance curve and deviation analysis. Results: it was found that: (i) SVM-based deterioration model used from its regression approach is suitable to predict critical structural conditions of uninspected sewer pipes because this model showed a PLR value around 6.8 (the highest value among the predictions of all structural conditions for both models) and 74 % of successful predictions for the first 100 pipes with the highest probability of being in critical conditions; and (ii) SVM-based deterioration model used from its classification approach is suitable to predict other structural conditions because this model showed homogeneous PLR values for the prediction of all structural conditions (PLR values between 1.67 and 3.88) and deviation analysis results for all structural conditions are lower than the ones for the SVM-based model from its regression approach.
目的:本文主要研究:(1)从支持向量机的回归方法出发,建立了一种基于支持向量机的劣化模型,将下水道管道结构状态预测与等级分类分离,并对CCTV检查中发现的故障进行评分预测;(ii)将所提模型的预测结果与基于SVM分类任务的劣化模型的预测结果进行对比,从不同角度探讨两者预测的优缺点。材料和方法:波哥大的下水道网络是本工作的案例研究,其中考虑了由CCTV检查的5031条管道的特征组成的数据集(由GIS获得),以及外部变量(例如,年龄,污水和道路类型)的信息。使用概率密度函数(PDF)将CCTV中发现的故障给出的分数转换为结构等级。此外,采用阳性似然率(positive likelihood rate, PLR)、性能曲线和偏差分析三种技术从不同角度对预测结果进行评价。结果发现:(1)基于支持向量机的劣化模型能较好地预测未经检验的污水管道的临界结构状态,该模型的PLR值在6.8左右(两种模型预测的所有结构状态中最高),对前100个管道处于临界状态的概率最高的预测成功率为74%;(ii)该分类方法所采用的基于svm的劣化模型也适用于其他结构工况的预测,因为该模型对所有结构工况的预测PLR值均为均匀的(PLR值在1.67 ~ 3.88之间),且所有结构工况的偏差分析结果均低于基于svm的回归方法模型的偏差分析结果。
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引用次数: 0
Four-quadrant Characterization of Hydrodynamic Phenomena in a Low Specific Speed Centrifugal Pump 低比转速离心泵流体动力现象的四象限表征
Q4 Engineering Pub Date : 2021-01-01 DOI: 10.11144/javeriana.iued25.fchp
H. Bolaños, F. Botero
Objective: Identify and characterize subsynchronous hydrodynamics phenomena in a low specific speed centrifugal pump based on its four-quadrant characteristic curve. Materials: A 1.5 HP ITT Goulds pump instrumented with pressure transductors, an accelerometer, a torque sensor and a tachometer. Flow rate measurement was done with an ultrasonic transit time clamp-on flow meter. Methods: Time and frequency domain analysis with phase analysis were used to identify spectral components linked to hydrodynamic phenomena such as rotating stall and surge. Results and discussion: This work approaches an alternative method to calculate the phase angle using pressure signals without filtering. Related with hydrodynamic phenomena, the evidence collected suggests the presence of rotating stall in some operation points of the four-quadrant characteristic curve. Furthermore, in the third quadrant, rotating stall coexist with surge. Conclusions: The instrumentation and methods regarded in this work allow to collect evidence to identify in-phase and out of phase subsynchronous hydrodynamic phenomena. The classic cross-correlation-based method was improved to ease the diagnosis of subsynchronous phenomena by visual inspection. A new quantitative approach was introduced to detect subsynchronous phenomena, based on the Fourier analysis; it was validated with a case study for which the classical method was not suitable.
目的:利用低比转速离心泵的四象限特性曲线,识别和表征低比转速离心泵的亚同步流体动力学现象。材料准备:一台1.5 HP的ITT古尔德泵,配有压力传感器、加速度计、扭矩传感器和转速计。流量测量是用超声波传输时间钳式流量计完成的。方法:采用时域、频域分析和相位分析相结合的方法,识别与旋转失速和喘振等流体动力现象相关的频谱成分。结果和讨论:本工作探讨了一种利用压力信号不加滤波计算相角的替代方法。结合水动力现象,收集到的证据表明,在四象限特征曲线的一些操作点存在旋转失速。此外,在第三象限,旋转失速与喘振并存。结论:本研究采用的仪器和方法可以收集证据来识别同相和非同相的次同步水动力现象。对经典的基于互相关的方法进行了改进,以简化视觉检测对亚同步现象的诊断。提出了一种新的基于傅里叶分析的次同步现象定量检测方法;通过实例分析验证了该方法的有效性。
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引用次数: 0
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